Foreign Nonindigenous Carps and Minnows (Cyprinidae)

in the United States – A Guide to their Identification,

Distribution, and Biology

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2005-5041

Foreign Nonindigenous Carps and 

Minnows (Cyprinidae) in the United 

States—A Guide to their Identification, 

Distribution, and Biology

By Pamela J. Schofield, James D. Williams, Leo G. Nico, 

Pam Fuller, and Matthew R. Thomas

Prepared in cooperation with the 

U.S. Fish and Wildlife Service

Scientific Investigations Report 2005-5041

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2005

For sale by U.S. Geological Survey

Information Services

Box 25286, Denver Federal Center

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Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not 

imply endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright 

owners to reproduce any copyrighted materials contained within this report.

Suggested citation:

Schofield, P.J., Williams, J.D., Nico, L.G., Fuller, P., and Thomas, M.R., 2005, Foreign Nonindigenous Carps 

and Minnows (Cyprinidae) in the United States—A guide to their Identification, Distribution, and Biology: 

U.S. Geological Survey Scientific Investigations Report 2005-5041, 103 p. 

Cover fish plate artwork: Joseph R. Tomelleri

Title page photograph courtesy of: Leo G. Nico

Layout/editing: Twila D. Wilson, USGS

Graphic production: Ronald S. Spencer, USGS
iii

Introduction 1

Foreign Cyprinids Treated in this Guide 2

What is a Cyprinid? 3

Introduced Versus Native Cyprinids 3

Other Fishes 3

Reporting Discovery of Nonindigenous Species 4

Methods 4

Taxonomy 4

Meristic and Morphometric Measures 4

Pharyngeal Teeth 4

Museum Specimens 5

Maps 5 

Key to Species 7

Table of Characters 14

Species Accounts 17

Goldfish (Carassius auratus) 19

Crucian Carp (Carassius carassius) 25

Grass Carp (Ctenopharyngodon idella) 31

Spawning Requirements of Chinese Carps (Silver, Grass, Bighead, and Black) 34

Common Carp (Cyprinus carpio) 39

Silver Carp (Hypophthalmichthys molitrix) 45

Bighead Carp (Hypophthalmichthys nobilis) 51

Ide (Leuciscus idus) 55

Black Carp (Mylopharyngodon piceus) 59

Bitterling (Rhodeus sericeus) 63

Rudd (Scardinius erythrophthalmus) 67

Tench (Tinca tinca) 73

Acknowledgments 77

Addendum 77

References Cited 79

Appendix A—Foreign cyprinids established or reported from the United States 93

Appendix B—Meristics of foreign nonindigenous cyprinids and selected hybrids 97

Appendix C—Nonindigenous aquatic species reporting form 103

Abbreviated diagnostic key to foreign nonindigenous cyprinids of the 

United States Inside back cover
iv

Plates

1. Map showing native distribution of the Family Cyprinidae 2

2-12. Maps showing distribution of foreign nonindigenous cyprinids in the United States for:

2. Goldfish 23

3. Crucian Carp 29

4. Grass Carp 38

5. Common Carp 44

6. Silver Carp 49

7. Bighead Carp 54

8. Ide 58

9. Black Carp 62

10. Bitterling 66

11. Rudd 71

12. Tench 76

Figures

1-10. Photographs or images depicting: 

1. Examples of nonindigenous cyprinids, showing those having a long dorsal fin 

with 13 or more branched rays, and those having a short dorsal fin with 12 or 

fewer branched rays 7

2. Head of Common Carp, showing two fleshy barbels near corner of jaw 7

3. Pharyngeal teeth of Common Carp and Goldfish 8

4. Concave dorsal fin of Goldfish, and convex dorsal fin of Crucian Carp 8

5. Head of Tench, showing single barbel near corner of jaw 9

6. Ventral keels of Silver Carp and Bighead Carp 10

7. Fused, sponge-like gill rakers of Silver Carp, and slender, comblike rakers of 

Bighead Carp 11

8. Keel of Rudd 12

9. Pharyngeal teeth of Grass Carp and Black Carp 13

10. Body cavity linings of Grass Carp and Black Carp 13

11. Goldfish 19

12. Pharyngeal teeth 19

13. Cultured (fancy) form 21

14. Wild (olivaceous) form 21

15. Crucian Carp 25

16. Deep-bodied form 26

17. Slender (humilis) form 26

18. Pharyngeal teeth 27
19. Grass Carp 31

20. Pharyngeal teeth 31

21. Subadult male 32

22. Adult 32

23. Adult 32

24. Common Carp 39

25. Pharyngeal teeth 39

26. Scaled variety 41

27. Mirror variety 41

28. Leather variety 41

29. Ornamental Koi in a pond at Lí Yuán Garden, Suzhou, People’s Republic 

of China 42

30. Silver Carp 45

31. Ventral keel 45

32. Pharyngeal teeth 46

33. Juvenile 46

34. Adult 46

35. Bighead Carp 51

36. Ventral keel 51

37. Pharyngeal teeth 52

38. Juvenile 52

39. Ide 55

40. Pharyngeal teeth 55

41. Black Carp 59

42. Black Carp from the species’ native range in the Chang (Yangtze) River Basin, 

Hunan Province, People’s Republic of China 60

43. Pharyngeal teeth 60

44. Bitterling 63

45. Pharyngeal teeth 63

46. Rudd 67

47. Pharyngeal teeth 67

48. Adult 68

49. Ventrolateral and posterior aspect of abdomen showing a scaled keel in 

Rudd, a partially scaled keel in hybrid Rudd X Golden Shiner, and a naked 

keel in Golden Shiner 68

50. Tench 73

51. Pharyngeal teeth 73

52. Tench taken by anglers from two sites in Europe: Willis’s Lake in Belfast, 

Northern Ireland, and in Belgium 74
vi

Conversion Factors

Multiply By To obtain

centimeter (cm) 0.3937 inch

meter (m) 3.281 foot

kilometer (km) 0.6214 mile

kilogram (kg) 2.2046 pound

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) by:

°F = 1.8 x °C + 32

Abbreviations and Acronyms

< less than

> more than

HUC USGS Hydrologic Unit Code

USGS U.S. Geological Survey

U.S. United States
Introduction

The family Cyprinidae (carps and minnows) is 

naturally distributed throughout most of the world except 

Australia and South America (plate 1). It is the largest 

family of freshwater fishes with about 2,010 species in 

210 genera. Most cyprinids (about 155 genera and 1,060 

species) are found in Eurasia (Nelson, 1994). About 

300 species in 50 genera are native to North America 

(Canada, Mexico, United States; Nelson and others, 

2004). The high diversity and expansive distribution of 

cyprinids have contributed to a long history of human 

use (of both cultured and wild-caught stocks) as food, 

bait, sport, forage, and ornamentals. A few species 

are used to control nuisance plants or other problem 

organisms (for example, disease-carrying snails). 

Cyprinids exhibit considerable variation in morphology, diet, and habitat use. The largest member of 

the family is the Giant Barb (Catlocarpio siamensis) 

of southeastern Asia, which may reach almost 3 m 

total length (TL) (Smith, 1945). In contrast, the miniature translucent species Danionella translucida from 

Myanmar (formerly Burma) attains only 12 mm standard 

length (SL), and is the smallest freshwater fish known 

(Roberts, 1986; Britz, 2003). Trophic diversity is also 

great, and the family includes planktivores (Bighead 

Carp, Hypophthalmichthys nobilis, and Silver Carp, 

Hypophthalmichthys molitrix), herbivores (Grass 

Carp, Ctenopharyngodon idella), piscivores (Colorado 

Pikeminnow, Ptychocheilus lucius), and omnivores 

(Common Carp, Cyprinus carpio). Many species have 

specialized diets, which are reflected in particular 

morphological adaptations (for example, the Black Carp, 

Mylopharyngodon piceus, has pharyngeal teeth modified 

for crushing mollusks). Cyprinids live in a wide variety 

of habitats from stagnant ponds and small streams to 

large lakes and swift-flowing rivers.

This guide was designed to benefit biologists and 

others interested in nonindigenous fishes by providing 

information for the identification of foreign cyprinids 

introduced into the U.S. In addition to providing identification keys and descriptions of distinguishing characteristics, we give details concerning distribution and 

environmental biology. This guide is a valuable resource 

for several reasons: 

(1) The number and variety of foreign fishes introduced into the U.S. has increased dramatically in the past 

few decades;

(2) Several introduced cyprinids have caused, or 

have the potential to cause, environmental or economic 

harm; and 

(3) Some foreign cyprinids superficially resemble 

native cyprinids or other (native or introduced) fishes. 

Consequently, introduced cyprinids may be misidentified 

or may not even be recognized as non-natives. 

Correct identification is critical in documenting 

the occurrence and dispersal of foreign species and in 

rapidly responding to the appearance of new foreign 

species. As learned during recent decades, a swift 

response is critical to eliminate and/or control harmful 

non-native fishes before they become widespread and 

abundant. 

By Pamela J. Schofield, James D. Williams, Leo G. Nico, Pam Fuller, and Matthew R. Thomas

Foreign Nonindigenous Carps and Minnows (Cyprinidae) 

in the United States—A Guide to their Identification, 

Distribution, and Biology
Foreign Cyprinids Treated in this Guide

Eleven foreign nonindigenous cyprinids are 

included in this guide. Eight species have established 

breeding populations in the U.S. (Goldfish, Grass Carp, 

Common Carp, Silver Carp, Bighead Carp, Bitterling, 

Rudd, and Tench). Three species are not known with 

certainty to have reproducing populations (Black Carp, 

Crucian Carp, Ide). There is mounting evidence suggesting that Black Carp is either already established in 

the wild or that it will become established in the near 

future (Nico and others, 2005). The Crucian Carp was 

reported to be thriving in Chicago, Illinois, in the early 

1900s (Meek and Hildebrand, 1910); however, it is no 

longer believed to exist there (Smith 1979). Although 

there are currently no documented reproducing populations in the U.S., there is a possibility that Crucian Carp 

is established but has been misidentified or confused 

with the morphologically similar Goldfish. Also, recent 

interest in culturing Crucian Carp for the live food fish 

trade raises the possibility of future introductions. Ide 

was included based on records of multiple introductions and one established population in Connecticut that 

was eradicated (Fuller and others, 1999). However, Ide 

may still be present, but undetected, in other drainages. 

Although we include detailed information and 

accounts for a few foreign cyprinid species not yet 

established in the U.S. (for example, Crucian Carp), this 

guide does not provide information for the identification 

of several other foreign cyprinids that have been found 

or reported in the U.S. These excluded species include 

ones that either never became established, or those 

that only temporarily formed reproducing populations 

and then subsequently disappeared. The Zebra Danio 

(Brachydanio rerio) is one example; it was reported to 

have a single reproducing population in a spring system 

in New Mexico (Sublette and others, 1990; Fuller and 

others, 1999), but is no longer extant (Nelson and others, 

2004). The Zebra Danio was also reported in the open 

waters of California, Connecticut, and Florida (Fuller 

and others, 1999), as the result of escapes from fish 

farms or aquarium releases; however, no evidence of 

reproduction has been reported. Two ornamental species 

from Asia, the Blackspot Barb (Puntius filamentosus) 

and the Green Barb (Puntius semifasciolatus), had 

reproducing populations in Nu’uanu Reservoir No. 2 in 

Oahu, Hawaii. However, neither species has been seen 

since the drought of 1984 when the reservoir almost 

dried (Yamamoto and Tagawa 2000). A few other foreign 

cyprinids have been reported in open waters of the U.S., 

but are not known to maintain reproducing populations 

appendix A). 

Plate 1. Native distribution of the Family Cyprinidae (in dark blue).

 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
What is a Cyprinid?

Cyprinids are not always easy to distinguish from 

other fishes. Basic cyprinid characteristics include 

no teeth on the jaws, a single dorsal fin, pelvic fins 

in an abdominal position, pectoral fins low on the 

side, and no adipose fin. The first full-length ray of 

the dorsal and anal fins is hardened into a spine-like 

structure in some foreign cyprinids (for example, the 

Common Carp, Crucian Carp, and Goldfish). Native 

North American cyprinids lack a spine-like ray, except 

certain genera endemic to the desert southwest (such as 

the Plagopterus, Meda, and Lepidomeda). Cyprinids 

have 19 principal caudal-fin rays (17 branched, 2 

unbranched). The scales are cycloid and the lateral-line 

system is typically well developed. The head typically 

has no scales. Cyprinids do not have jaw teeth; instead, 

they use a pharyngeal apparatus to process food. This 

apparatus consists of a modified thick fifth pharyngeal 

arch that bears teeth and a chewing (masticatory) pad 

that is located on roof of the pharynx. The size and shape 

of the arch and teeth are closely tied to the diet of the 

species. The lips usually are thin, but in some cyprinids 

they are enlarged and sucker-like or even lobed. Most 

cyprinids lack barbels on the lips but they are present in 

a few genera, including a few native to North America. 

A swim (gas) bladder is always present and usually twochambered. Cyprinids and several related groups have 

a Weberian apparatus comprised of modified anterior 

vertebrae that connect the swim bladder to the inner 

ear. The Weberian apparatus transmits sound vibrations to auditory receptors in the brain and is thought to 

give cyprinids a keen sense of hearing. Most cyprinids 

have a typical minnow-shaped body form, but some are 

elongated, some compressed, and others robust. Many 

cyprinids are sexually dimorphic. For example, males 

of many species become brightly colored during the 

breeding season, and may temporarily develop nuptial 

(breeding) tubercles. Females may also develop breeding 

tubercles, but these are generally less well developed 

than those of the males. Proliferation and distribution of 

tubercles on the body varies between sexes and among 

species, often appearing on parts of the head, body, and 

fins (Etnier and Starnes, 1993; Jenkins and Burkhead, 

1994; Nico and others, 2005).

Introduced Versus Native Cyprinids

Because the family is so diverse, there is no single 

set of characteristics that distinguishes all introduced 

cyprinids from native North American cyprinids. 

Nevertheless, a few introduced cyprinids are distinctive 

and can easily be identified as non-natives. Among these 

are Common Carp, Goldfish, and Crucian Carp, which 

have a stout, spine-like ray in the front part of their 

dorsal and anal fins. Only a few North American species 

native to the desert southwest possess similar spine-like 

rays. In addition, some foreign cyprinids have relatively 

long dorsal fins with 13 or more branched rays. In 

contrast, almost all native cyprinids have short dorsal 

fins, with 11 or fewer (usually 7-9) branched dorsal-fin 

rays. Moreover, most foreign cyprinids are mediumor large-sized fishes, reaching over a meter long. In 

contrast, the majority of native cyprinids are fairly small 

and few species exceed 15 cm TL. One notable exception is the native (and critically endangered) Colorado 

Pikeminnow, a species historically known to reach 

almost 2 m long and weigh 40 kg (Minckley 1973).

Other Fishes 

Only a few other non-cyprinid fishes native to North 

America are superficially similar to foreign cyprinids. 

Some members of the sucker family (Catostomidae), 

such as buffalos (Ictiobus) and carpsuckers (Carpiodes), 

resemble the Common Carp, Goldfish, and Crucian 

Carp. Suckers share some cyprinid characteristics, 

including pharyngeal teeth, cycloid scales, and nuptial 

tubercles on breeding males. Suckers also lack jaw teeth 

and adipose fins. However, suckers can be distinguished 

from cyprinids by the number of principle caudal-fin 

rays (18 in suckers, 19 in cyprinids). Barbels are present in some cyprinids, but are always absent in suckers. 

Additionally, suckers lack spine-like dorsal- and analfin rays that are characteristics of the Common Carp, 

Goldfish, and Crucian Carp. The pharyngeal teeth of 

suckers are typically long and fine, are arranged in a 

single comb-like row along the arch, and number 10 

or more per side. In cyprinids, the pharyngeal teeth are 

often (but not always) stout or molar-like, and number 

less than 10 per side. The mouth of most suckers opens 

ventrally, and the lips are generally thick and fleshy 

(Jenkins and Burkhead, 1994). 

Introduction 
Reporting Discovery of Nonindigenous Species

The collection of any nonindigenous cyprinid 

should be reported to state game and fish agencies and to 

the Nonindigenous Aquatic Species database (http://nas.

er.usgs.gov; appendix C). For those wishing to report a 

new record, be aware that positive identification is of 

the utmost importance. Consequently, we urge that the 

specimen be retained if possible or at least well documented with photographs. It is especially helpful for 

photographic images to be well-focused and to include 

shots of the entire fish from various angles as well as 

close-up views of the head and fins.

Methods

Taxonomy

Scientific names and authorities were taken from 

“A Catalog of the Species of Fishes” (Eschmeyer and 

others, 1998, and amendments) available through 

the California Academy of Science (online at: http://

www.calacademy.org/research/ichthyology/catalog/ 

fishcatsearch.html). Common names of fishes follow 

Nelson and others (2004).

Meristic and Morphometric Measures

Methods of recording meristic (count) and morphometric (measurement) data were standardized by Hubbs 

and Lagler (1958) and reviewed in Strauss and Bond 

(1990). Additionally, several publications that provide 

information on fishes of particular regions or states 

list useful details regarding identification, including 

standard formats for expressing meristics and morphometrics (for example, Page and Burr, 1991; Etnier and 

Starnes, 1993; Jenkins and Burkhead, 1994; Ross, 2001; 

Boschung and Mayden, 2004). Meristic characteristics 

are variable within and among the cyprinids treated in 

this guide. Thus, meristic data from a number of sources 

are included for each species, including data from 

both native and introduced populations when available 

(appendix B). These data were reproduced as given 

by the original authors. Although most of the original 

reports follow the standards of Hubbs and Lagler (1958) 

and Strauss and Bond (1990), some did not (especially 

those in foreign publications) and, therefore, inconsistencies may exist. For detailed information on methods of 

data reporting, the cited authority should be consulted. 

Fin-ray counts, comprised of unbranched and 

branched rays, are often useful in the diagnosis of 

fish species. When reporting fin-ray counts, the first 

set of Roman numbers represents the number of soft 

unbranched rays. The second set (in parentheses) represents the number of soft branched rays. For example, a 

fin with three unbranched rays and eight branched rays 

would be represented as: iii (8). The spine-like ray present in the dorsal and anal fins of some foreign cyprinids 

(for example, Common Carp, Goldfish, Crucian Carp) 

and a few native fishes is counted as an unbranched ray. 

Because the unbranched rays of the dorsal and anal fins 

are often difficult to discern, most North American fish 

books report only a single number representing a single 

unbranched ray plus all the branched rays. The last two 

branched rays usually share a common basal skeletal 

element and are counted as one.

Counts of gill rakers are based on the first (outer) 

gill arch and normally performed using the outer arch 

on the left side of fish. Gill rakers are often aligned in 

two rows on each gill arch, an outer row of longer rakers 

and an inner row of short stubs. Only rakers on the outer 

row are counted, including the smallest in the outer-row 

series at top and bottom of the arch (Calliet and others, 

1986). Some authors give either upper and lower limb 

counts, or inner and outer (anterior and posterior) counts, 

and those data are listed in this guide.

Length of fishes is conventionally given in either 

standard (SL) or total length (TL). Standard length is 

the straight-line distance from the tip of the snout to the 

posterior end of the vertebral column. The end of the 

vertebral column can be located by laterally flexing the 

caudal fin at its base. The crease in the flesh at the base 

of the caudal fin marks the end of the vertebral column 

(hypural plate) and the beginning of the caudal fin. 

Total length is the straight-line distance from the tip of 

the snout to the posterior tip of the longest caudal-fin 

rays. North Americans typically measure total length 

(TL) with the caudal fins compressed dorso-ventrally, 

resulting in a measure slightly longer than if the caudal 

fins are left in their natural position (Anderson and 

Neumann, 1996). Unfortunately, many authors do not 

report the method used to determine total length.

Pharyngeal Teeth

Cyprinids do not have jaw teeth. Instead, they rely 

on their pharyngeal teeth and masticatory pads to crush 

or process their food. The number, size, and shape of 

the pharyngeal teeth are generally species specific. 

 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
In cyprinids, the fifth branchial arches are located on the 

floor of the posterior pharynx, anterior to its junction 

with the esophagus. To clearly view the pharyngeal teeth, 

it is often necessary to extract the pharyngeal arch. This 

can be accomplished by removing the operculum, gills, 

and other surrounding tissues. Alternately, the gills and 

operculum can be folded forward to expose the pharyngeal teeth. Much care must be exercised to extract an arch 

without damaging the teeth and resulting in an incorrect 

tooth count. In this guide, dorsal-view illustrations of 

pharyngeal teeth are given in each species account. The 

number of pharyngeal teeth is represented by a standardized formula. For example, a count of 0,4-4,0 denotes 

one inner row of four teeth on each arch. Alternately, a 

count of 1,1,3-3,1,1 denotes three rows on each side, with 

three teeth in the innermost row and two outer rows with 

one tooth each. By convention, pharyngeal teeth are read 

from the outside of the left to the outside of the right. 

Some species show dramatic changes with growth, and 

young individuals sometimes have pharyngeal teeth quite 

different from adults. The pharyngeal teeth illustrated in 

this guide are those of adult fish. 

Museum Specimens

Preserved specimens referenced in this study are 

from the following sources: AUM (Auburn University 

Museum Fish Collection, Auburn, Alabama); SIUC 

(Southern Illinois University at Carbondale, Fluid 

Vertebrate Collection, Carbondale, Illinois); TU (Tulane 

University Museum of Natural History Fish Collection, 

New Orleans, Louisiana); UF (Florida Museum of 

Natural History, Department of Ichthyology, Gainesville, 

Florida). 

Maps

The U.S. distribution of each foreign cyprinid 

species is given on a map plate in the corresponding 

species account. Distribution information is presented by 

drainage and by state, each coverage indicating different 

levels of information. 

Distribution by drainage.—U.S. Geological 

Survey Hydrologic Unit Codes (HUCs) were used as 

a base to build maps. This is a nationwide system that 

delineates watersheds based on surface hydrologic 

regions (for more information, see: http://nas.er.usgs.

gov/hucs.asp). Maps in this guide use a combination of 

6-digit and 8-digit HUCs. The maps distinguish between 

HUCs where there is evidence of natural reproduction 

in the wild (coded as “reproducing”) and those where 

the species has been reported, but without evidence of 

reproduction (coded as “reported”). The distinction 

is important. Once a nonindigenous fish establishes 

a reproducing population, it may persist indefinitely, 

becoming a permanent addition to the fauna. 

(1) Reproducing species.—A species is coded as 

“reproducing” within a HUC if a naturally reproducing population is present. These drainages are 

color-coded red on the maps. Usually, evidence for 

reproduction is based on presence of adult fish as 

well as reports that eggs, larvae, or small juveniles 

have been collected within the HUC. Sometimes 

reproduction is inferred by persistence of a species 

in a particular water body over an extended period 

of time. Persistent reproduction is usually habitat 

dependent. Some of the species in this guide are 

capable of reproducing in still waters, such as 

lakes and ponds (Common Carp, Goldfish, and 

Tench). Other species, such as the Chinese carp 

(Grass Carp, Silver Carp, Bighead Carp, and Black 

Carp), naturally spawn in rivers. 

(2) Reported species.—HUCs are coded as “reported” 

if the species has been collected, stocked, or 

observed in one or more parts of a drainage, but 

no evidence exists that the species is successfully 

reproducing. These drainages are color-coded pink 

on the maps. Failed historical introductions (that 

are known to us) are included in this category.

(3) Eradicated species.—Eradication is the complete 

elimination of all individuals in a given population. Many eradication attempts fail, as aquatic 

organisms are especially difficult to completely 

remove from a system despite vigorous and costly 

efforts to eliminate them. Years of monitoring are 

usually required to assure no survivors persist. In 

some cases, the source of introduction is never 

identified, consequently individuals continue to 

repopulate the area. In general, the only successful eradication projects are ones directed at fish 

confined in small, relatively closed systems, such 

as a pond or smaller, somewhat isolated reservoirs 

or drainages (see account on Ide, Leuciscus idus). 

In larger and unconfined water systems (rivers, 

canal networks, estuary complexes) the possibility of successful eradication is extremely low (or 

impossible) and the cost of such projects high. 

There is little hope of completely eradicating some 

widely-ranging nuisance fishes, especially with the 

techniques currently available.

Methods 
Eradication attempts are often poorly documented 

(typically in the gray or unpublished literature), making 

it difficult to evaluate their success. Additionally, reports 

of eradications from selected sites do not always include 

information on whether the species continued to survive 

in other parts of the drainage. The confusion and shortage of information complicate the task of tracking 

and accurately mapping changes in the distribution of 

introduced populations. For example, Dill and Cordone 

(1997) reported that a reproducing population of Tench 

was eliminated from a small farm pond in the Trinity 

River drainage in California, but did not comment on 

whether the species was known to exist or was reproducing elsewhere in that drainage. A later report (Moyle 

2002) indicated there were no recent records for Tench 

in the Trinity River. Thus, it is unclear whether the local 

eradication effort reported by Dill and Cordone (1997) 

removed the only reproducing population of Tench 

or whether other reproducing populations of Tench 

throughout the drainage simply died out over time. 

Distribution by state.—In addition to providing the 

distribution of each species by drainage, we also include 

distribution information for all 50 states. States colorcoded green represent those from which the species has 

been recorded at least once from natural waters within 

state borders. In some instances, the record of occurrence may be nonspecific, with no information about 

the precise drainage or location within the state where 

the species was reported, released, or captured. In such 

cases, the entire state is shaded green but no drainage is 

shaded. In contrast to the HUC units described above, 

the state colors do not provide information concerning 

the population status of the species (that is, reproducing versus non-reproducing). If a foreign cyprinid is 

known only from one site in a drainage, then the entire 

drainage is color coded (either red or pink). Many HUC 

units cross state boundaries. For additional information 

on state-by-state occurrence of foreign cyprinids, see 

appendix A.

Water bodies included in the coverage.—

Distributions delineated on the maps pertain only 

to records from the wild, including habitats that are 

natural (rivers, lakes) or artificial (canals, farm ponds, 

reservoirs). Maps do not include records based on 

captive indoor settings or outdoor ponds and tanks at 

aquaculture facilities, as the focus of the database is to 

document wild-caught non-native fishes. However, it 

has become increasingly evident that documentation of 

the location of aquaculture facilities as well as the fish 

stocks cultured there is important due to the likelihood 

of escape from outdoor ponds to nearby open systems. 

Unfortunately, this data is often difficult to obtain.

Source of map distribution data.—Data used 

to create these maps were primarily derived from the 

Nonindigenous Aquatic Species (NAS) database at the 

U.S. Geological Survey and from the closely related 

publication on nonindigenous fishes by Fuller and others 

(1999). The database is built from a variety of sources, 

including scientific literature, published and unpublished 

reports, and museum specimens. The database also relies 

on information from personal communications with 

scientists and others, as these sources are often the most 

recent (or only) documentation of a species’ occurrence 

in a particular area. We have attempted to make the maps 

in this guide as up-to-date as possible. Nevertheless, we 

may not be informed of all occurrences of nonindigenous cyprinids. Moreover, the distribution of nonnative fishes frequently changes over time, with many 

species expanding their ranges. Consequently, readers 

are reminded that distributions of introduced species 

are constantly in flux, so those who are attempting to 

identify a fish should not rule out a particular species 

simply because the map shows that it has not previously 

been reported from the area. 

Most of the distribution data provided in this 

guide can be found by querying the NAS database 

(http://nas.er.usgs.gov/queries). Summary collection 

information, including date, can be obtained by clicking on the dip-net icon. Detailed information about 

each collection can be found by clicking on the specimen ID. The database is constantly updated as new 

records are added and earlier records are reviewed 

and corrected. Individuals who have relevant information concerning the collection of nonindigenous 

cyprinids are asked to report their findings to state 

game and fish agencies and to the NAS database 

(appendix C; See subsection “Reporting the Discovery 

of Nonindigenous Fishes” at end of Introduction).

 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
1a. Dorsal fin long, with a stout, saw-toothed, spine-like ray anteriorly, followed by 13 or more 

branched rays (fig. 1A); anal fin also preceded by a stout, spine-like ray [Note: Spine-like 

rays preceded by one or a few short or rudimentary rays] ............................................................Go to 2

1b. Dorsal fin short, with 12 or fewer branched rays (fig. 1B); dorsal and anal fins without 

stout, saw-toothed spine-like ray...................................................................................................Go to 4

2a. One pair of fleshy barbels on each side of the head, located near corner of mouth on upper 

jaw, the anterior barbel slightly shorter (fig. 2); pharyngeal teeth molariform, in 3 rows 

(1,1,3-3,1,1; fig. 3A); color brassy to yellowish, with lower fins often yellow-orange; 

ornamental varieties may range in color from bright orange, red, black, to white or some 

combination of these; some genetic strains with only a few large scales (“mirror carp”) or 

lack scales entirely (“leather carp”).

.......................................................................................... Common Carp (Cyprinus carpio) Page 39

Figure 1. Examples of nonindigenous cyprinids having (A) a long dorsal fin with 13 or more branched rays, and 

(B) a short dorsal fin with 12 or fewer branched rays.

Figure 2. Head of Common Carp, showing two 

fleshy barbels near corner of jaw.

(A) (B) 

 

Key to Species
2b. No barbels around the mouth; pharyngeal teeth in one row (0,4-4,0; fig. 3B); body relatively 

deep and compressed (except in some stunted forms that are relatively elongate or in certain 

ornamental forms exhibiting bizarre body shapes)........................................................................Go to 3

3a. Upper margin of dorsal fin straight or slightly concave (fig. 4A); caudal fin deeply emarginate; 

rakers on first gill arch 37-52; spine-like ray of dorsal fin deeply serrated on posterior margin 

with 10-11 teeth (denticles) becoming markedly larger towards tip of ray; lining of abdominal 

cavity (peritoneum) darkly pigmented; no dark spot at base of caudal fin; color of wild types 

typically olivaceous or olive bronze, but cultured varieties may be white, silver, pink, gold, 

brassy gold, orange, or blotched orange, black, or a combination of these colors.

................................................................................................. Goldfish (Carassius auratus) Page 19

3b. Dorsal-fin margin slightly convex (fig. 4B); caudal fin slightly emarginate; rakers on first gill 

arch 22-33; spine-like ray of dorsal fin serrated on posterior margin, typically with 28-29 teeth 

(denticles) of about the same size; lining of abdominal cavity (peritoneum) light; a dark spot 

at the base of the caudal fin, more evident in juveniles but sometimes also present on adults; 

color typically coppery-gold but may be silvery-white.

...................................................................................... Crucian Carp (Carassius carassius) Page 25

(A) Common Carp (B) Goldfish

Figure 3. Pharyngeal teeth: (A) Common Carp [1,1,3-3,1,1], and (B) Goldfish [0,4-4,0]. 

Figure 4. Concave dorsal fin of (A) Goldfish, and convex dorsal fin of (B) Crucian Carp.

(A) Goldfish (B) Crucian Carp

 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
4a. Scales small, 70 or more in lateral line..........................................................................................Go to 5

4b. Scales large, fewer than 65 in lateral line......................................................................................Go to 7

5a. A single small, thin barbel on each side of the head, on upper jaw near corner of mouth (fig. 5); 

belly rounded, without keel on venter; posterior margin of caudal fin straight or slightly forked; 

color of body variable, dark brown to black, to dark green or greenish yellow, often bronze or 

yellow below; one variety (“Golden Tench”) uniformly golden yellow with dark blotches.

..................................................................................................................Tench (Tinca tinca) Page 73

5b. No barbels around the mouth; keel present, either along entire midline of belly or posterior 

to pelvic fin base; caudal fin distinctly forked; body color generally gray or silver above and 

white or cream below ....................................................................................................................Go to 6

6a. Body color on sides generally uniformly gray or silver, without scattered irregularly shaped dark 

blotches; ventral keel long, extending along midline of belly from anus forward almost to junction 

of gill membranes (fig. 6A); rakers on first gill arch fused into a sponge-like structure (fig. 7A); 

when apressed, pectoral fin does not extend to base of pelvic fin.

............................................................................Silver Carp (Hypophthalmichthys molitrix) Page 45

6b. Body color on sides gray or silver with numerous small, irregularly shaped dark blotches; ventral 

keel relatively short, extending from anus forward to near origin of pelvic fins (fig. 6B); rakers 

on first gill arch long and slender, comb-like, not fused into a sponge-like structure (fig. 7B); 

when apressed, pectoral fin extends beyond pelvic fin origin.

......................................................................... Bighead Carp (Hypophthalmichthys nobilis) Page 51

7a. Lateral-line scales fewer than 50.................................................................................................. Go to 8

7b. Lateral-line scales 55-63..........................................................................Ide (Leuciscus idus) Page 56

Figure 5. Head of Tench, showing single 

barbel near corner of jaw.

Key to Species 
Figure 6. Ventral keels: (A) Silver Carp, and (B) Bighead Carp.

(A) Silver Carp

(B) Bighead Carp

10 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
8a. Keel present on belly between anus and base of pelvic fins (fig. 8). 

...................................................................................... Rudd (Scardinius erythrophthalmus) Page 67

8b. No keel on belly.............................................................................................................................Go to 9

Figure 7. Gill rakers: (A) fused, sponge-like gill rakers of Silver Carp, and (B) slender, 

comblike rakers of Bighead Carp. (Gill raker photographs courtesy of David Ostendorf, 

Missouri Department of Conservation.)

(A) Silver Carp

(B) Bighead Carp

Key to Species 11
9a. Pored scales in lateral line 35-45; origin of anal fin posterior to dorsal fin base; membranes 

of dorsal and anal fin of adults without red pigment; midlateral stripe on caudal peduncle 

absent; body cylindrical; adults often over 1 m TL.....................................................................Go to 10

9b. Pored scales in lateral line fewer than 12; origin of anal fin beneath dorsal fin base; membranes 

of dorsal and anal fins of adults with red pigment; distinct midlateral stripe present on caudal 

peduncle; body compressed, deep; adults rarely over 11 cm TL.

..................................................................................................Bitterling (Rhodeus sericeus) Page 63

10a. Pharyngeal teeth elongate, with prominent grooves or serrations on grinding surfaces, hooks 

sometimes present, teeth typically 2,5-4,2 (fig. 9A); body typically olivaceous or silvery-white, 

may be olive-brown above and silver to white below; most fins only lightly pigmented (dusky), 

never black; lining of body cavity (peritoneum) silvery with dark mottling, large areas may be 

darkly pigmented (fig. 10A); 12-16 rakers on first gill arch.

................................................................................. Grass Carp (Ctenopharyngodon idella) Page 31

10b.Pharyngeal teeth massive, molar-like, without hooks, generally smooth (not serrated or grooved), 

with wide masticatory surfaces, teeth typically in a single row with four or five on each side 

(fig. 9B), but two rows present in some individuals (in which case the outer row usually 

consists of a single small tooth, or very rarely two); body usually dark, often blue-gray or 

black, white or cream below; fins darkly pigmented, almost black; lining of body cavity 

(peritoneum) typically black (fig. 10B); 14-23 (usually 18-21) rakers on the first gill arch.

..................................................................................Black Carp (Mylopharyngodon piceus) Page 59

Figure 8. Keel of Rudd. Note: The native morphologically similar Golden Shiner has a similar keel 

(see fig. 49, p. 68).

12  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Figure 9. Pharyngeal teeth: (A) Grass Carp, and (B) Black Carp.

Figure 10. Body cavity linings: (A) Grass Carp, and (B) Black Carp.

(A) Grass Carp (B) Black Carp

(A) Grass Carp (B) Black Carp

Key to Species 13
Table of Characters.

[TL, total length; cm, centimeter; m, meter]

Scientific name Common 

name

Maximum 

adult size

 (TL)

Pharyngeal teeth Tooth morphology Barbels Body/fin pigmentation

Carassius auratus Goldfish 59 cm 0,4-4,0 Somewhat molar-like, but narrow and smoothedged, without extensive grinding surfaces absent Wild types typically olivaceous, but cultured varieties vary considerablyCarassius carassius Crucian Carp 64 cm 0,4-4,0 Not molariform, without flattened grinding 

surfaces

absent Body golden copper, darker dorsally; fins reddish; black spot at base of caudal (more evident 

in juveniles)

Ctenopharyngodon idella Grass Carp 1.5 m 2,5-4,2 or 2,4-5,2 Prominent parallel grooves on grinding surfaces absent Dark grey or olivaceous dorsally, to silvery white 

laterally

Cyprinus carpio Common Carp at least 1 m 1,1,3-3,1,1 Molariform, with flattened grinding surfaces on 

main teeth

present 

(two on 

each side)

Body color brassy to yellow; lower fins often yellow-orange; considerable variation in cultured varieties

Hypophthalmichthys molitrix Silver Carp at least 1 m 0,4-4,0 Grinding surfaces striated absent Sides plain, lacking scattered dark blotchesHypophthalmichthys nobilis Bighead Carp at least 1 m 0,4-4,0 Moderately long, bluntly rounded absent Sides with numerous small, irregularly shaped 

dark blotches

Leuciscus idus Ide 1 m 3,5-5,3 Smooth, not serrated absent Dark dorsally and laterally above lateral line; 

lower portion of sides and belly silver; paired fins reddish

Mylopharyngodon piceus Black Carp 2 m 0,4-5,0 or 0,5-4,0; 

sometimes with 1 or 2 small teeth in inner row

Massive, molar-like, smooth (not grooved), wide masticatory surfaces, no hooks

absent Body and fins blue gray to black; ventral surface 

of head and abdomen grayish white

Rhodeus sericeus Bitterling 11 cm 0,5-5,0 Serrate, hooked absent Dorsum gray-green; sides and belly silvery; fins 

pale orange; a gray-green stripe along mid-line of body from under dorsal fin to caudal peduncle

Scardinius erythrophthalmus Rudd 45 cm 3,5-5,3 Serrate, hooked absent Dorsum brassy; upper sides silvery; median fins 

blood red in large nuptial males

Tinca tinca Tench 80 cm 0,4-5,0 or 0,5-5,0 Molariform, with flattened grinding surfaces on 

main teeth; in juveniles wedge-shaped, slightly hooked at tip

present 

(one on 

each side)

Variable, dark brown, black, greenish or greenish yellow

14  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Table of Characters. (Continued)

Common 

Name Midventral keel Gill rakers Branched dorsal-fin rays Lateral line scales Branched anal-fin rays Pectoral fin rays Pelvic fin rays Vertebrae Peritoneum color

Goldfish none 37-52 13-19, with long, stout serrated 

spinelike ray preceded by 1-3 rudimentary rays; posterior margin of spinelike ray with 10-11 denticles

26-33 5-6 branched rays, preceded 

by a serrated spinelike ray and 1-2 rudimentary rays

14-18 7-9 25-31 blackish

Crucian Carp none 22-33 14-21, preceded by a stout, serrated 

spine and 2-3 rudimentary rays; posterior margin of spinelike ray with 28-29 fine denticles

28-37 5-8, preceded by a serrated 

spinelike ray and 1-2 rudimentary rays

14-16 8 31-34 light

Grass Carp none 12-16 7-8 34-45 8-10 14-20 7-8 ± 41 silvery with 

black blotches

Common Carp none 18-36 15-23 rays, preceded by a stout 

serrated spine and 2-4 rudimentary rays; serrated spinelike ray with 10-15 denticles 

32-40 

(except some 

domesticated 

varieties)

4-6, preceded by a serrated spine-like ray and 1-3 rudimentary rays

14-19 7-9 31-38

Silver Carp Present, smooth, extends 

forward from anus almost to junction of gill membranes

Rakers on front of first gill arch fused into a spongelike apparatus

7 91-124 11-14 16-17 7-8 ± 37

Bighead Carp Present, smooth, extends 

forward only to junction of pelvic fins

Long and slender, not fused

7-10 91-120 10-17 16-19 7-9 ± 38

Ide none 10-14 7-10 55-63 9-13 16-18 8 44-47Black Carp none 14-23 7-9 39-46 7-9 16-18 8 37-41 blackishBitterling none 9-16 7-13 0-10 pored; 

32-45 total

6-11 12-13 8 32-38

Rudd present, scaled 10-13 8-10 37-43 9-13 15-17 7 37-40 silveryTench none 10-16 6-9 70-120 scales 

deeply embedded in skin

5-9 13-18 35-44

Table of Characters 15
Anglers fishing for Carp and Goldfish in Beijing Canal, People’s Republic of China, 2004. (Photo by Leo G. Nico.)

16  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
 17

Species Accounts
Angler with Goldfish captured in canal in Beijing, People’s Republic of China, 2004. (Photo by Leo G. Nico.)

18  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Goldfish

Carassius auratus (Linnaeus 1758)

Description

The Goldfish (fig. 11) is a robust, medium-sized 

cyprinid that generally reaches 15-20 cm TL and weighs 

100-300 g (Szczerbowski, 2001). Maximum size is 

about 59 cm TL and 3 kg (IGFA, 2001). The lateral 

line is complete, typically with 26-33 scales (range 

25-36). The mouth is terminal, slightly oblique, and 

lacks barbels. The dorsal fin is long with iii-iv (13-19) 

rays, and a stout, spine-like ray precedes the branched 

rays. The anal fin has ii-iii (5-6) rays. The caudal fin is 

deeply emarginate and the belly lacks a keel. Pharyngeal 

teeth are in one row (0,4-4,0) and are somewhat molarlike, but narrow and smooth edged, without extensive 

grinding surfaces (fig. 12). Gill rakers on the first arch 

number 37-53. The peritoneum is blackish. Sexual 

dimorphism is not pronounced (Dombrovski, 1964, 

in Szczerbowski, 2001). Wild Goldfish are typically 

olive-green, gray, or silver; ornamental forms exhibit 

a range of colors (see section on variation, below). 

Breeding males may develop small nuptial tubercles 

Figure 11. Goldfish, SIUC 22609, 122.5 millimeter SL, from Alexander County, Illinois.

Figure 12. Pharyngeal teeth (0,4-4,0) of Goldfish, 

SIUC 22609, 122.5 millimeter SL, from Alexander 

County, Illinois. (Also see fig. 3, p. 8.)

on the operculum, dorsum, and pectoral fin rays (Coad, 

2005). These structures are white and small; often giving 

the false impression the fish is infected with the disease 

“ich.” Meristics for Goldfish are given in appendix B.

 19
Similar Species

The long dorsal fin of the Goldfish, with a 

strong, serrated, spinous ray followed by 13 or more 

branched rays, distinguishes it from most native North 

American cyprinids, which typically have fewer than 

11 rays and usually lack the spine-like ray. Goldfish 

superficially resemble suckers (family Catostomidae), 

particularly buffalos (genus Ictiobus) and carpsuckers (genus Carpiodes); however, suckers do not 

have spine-like rays in the dorsal and anal fins.

Among foreign nonindigenous cyprinids, the 

Goldfish most closely resembles the Common Carp and 

Crucian Carp. Goldfish lacks barbels, which readily 

distinguishes it from the Common Carp (that has two 

pairs of barbels). Differences between larval Goldfish 

and Common Carp were illustrated by Gerlach (1983). 

Goldfish is distinguished from Crucian Carp by its 

straight or slightly concave dorsal-fin margin, blackish peritoneum, a deeply emarginate caudal fin, and 

the absence of a spot at the base of the caudal fin. 

Crucian Carp has a slightly convex dorsal-fin margin, 

light peritoneum, a slightly emarginate caudal fin, 

and a blackish spot at the base of the caudal fin that is 

more apparent in juveniles. The posterior margin of the 

large, spine-like dorsal ray has 10-11 large denticles in 

Goldfish versus 28-29 small denticles in Crucian Carp. 

Additionally, the Goldfish is typically slightly less 

deep-bodied than Crucian Carp. The pharyngeal teeth 

of Goldfish and Crucian Carp are nearly identical.

Variation

The Goldfish exhibits a wide range of sizes, shapes, 

and colors of the body and fins. Much of the variation 

is the result of artificial breeding, and some is due to 

natural causes associated with age or growth changes. 

For example, as observed in many species, there is an 

increase in the number of gill rakers on the first arch 

with growth (Dombrovski, 1964, in Szczerbowski, 

2001). Artificial selection from a long history of culture 

has also intensified variability in body shape and color. 

The Goldfish was probably the first cultured fish; 

its domestication began thousands of years ago in 

China (Balon, 1995). The classic cultured form, known 

to aquarists as “Fancy Goldfish” (fig. 13), is reddish 

golden with yellow fins; however, artificial selection by 

breeders has produced a number of varieties for the pet 

trade (for example, Comets, Veiltails, and Shubunkins). 

Several varieties have been produced with body colors 

of red, white, gold, black, and combinations of these. 

Some varieties have been produced that lack a dorsal 

fin, others have greatly elongated fins (especially the 

caudal) or multiple fins (especially the caudal and anal), 

and some have telescoping eyes (for example, Pénzes 

and Tölg, 1983). Some cultivars may be variegated 

and some have no scales. These colorful forms are in 

contrast to the wild type, which is generally olivaceous, 

varying in color from gray-green, green-brown or gray 

(fig. 14). Wild populations of Goldfish often revert to 

olive-green coloration, presumably because the brightly 

colored ones are eliminated by bird and fish predators (Moyle, 2002; Wydoski and Whitney, 2003).

In treating Carassius auratus, recent authorities 

often recognize two subspecies: Carassius auratus 

gibelio (Bloch, 1783), commonly known as Prussian, 

Silver Crucian, European Goldfish, or Gibel Carp; 

and Carassius auratus auratus, generally referred 

to as Goldfish. However, the taxonomy of the genus 

Carassius is not fully understood due to a combination 

of confounding factors, including wide morphological 

variation within purported species, overlap in morphology between species (and also between subspecies), 

widespread introductions, high frequency of hybridization, and other genetic complexities such as triploidy 

(Fuller and others, 1999; Iguchi and others, 2003). In 

addition to other nomenclatural disagreements, some 

authors recognize gibelio as a separate species rather 

than a subspecies under C. auratus. According to 

Coad (2005), elongate specimens (morpha humilis) 

occur where fish density is high, and deep-bodied 

specimens (morpha vovki) occur where fish density is 

low; however, the author noted that the names humilis

and vovki have no taxonomic significance. To add to 

the confusion, Bănărescu (1964) described the same 

type variation in body shape for Carassius carassius (see section on variation under account on the 

Crucia Carp). Whether Carassius auratus is a highly 

variable species as opposed to a complex of multiple 

species may only be resolved by further investigation 

combining morphological and molecular analyses.

The Goldfish naturally hybridizes with Common 

Carp (see appendix B for meristics) and Crucian 

Carp, giving rise to individuals that are intermediate in morphology between the two parent species 

(Smith, 1979; Szczerbowski, 2001). A natural intergeneric hybrid of Barbus sharpeyi and Carassius 

auratus was recently described from a small lake 

in Iran (Al-Mukhtar and Al-Hassan, 1999, cited by 

Coad, 2005). However, there are no known hybrids 

with North American cyprinids. For a listing of other 

known hybrids between Goldfish and various Old 

World species, refer to Schwartz (1972, 1981).

20 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Reproduction

Sexual maturity is reached at 1-2 years of age, 

and reproduction occurs annually for about 6-7 years 

(Robison and Buchanan, 1988). Females scatter their 

adhesive eggs over vegetation, roots, or other fixed 

objects (Hensley and Courtenay, 1980; Robison 

and Buchanan, 1988). The Goldfish is a batch 

spawner, reproducing in the spring and summer when 

temperatures are above 16 °C (Robison and Buchanan, 

1988). Eggs take 3-7 days to hatch, depending on 

temperature (Wheeler, 1969; Moyle, 2002; Boschung 

and Mayden, 2004). Egg and larval development were 

described in Nakamura (1969) and Jones and others 

(1978). Exceptional camera lucida illustrations of egg 

and larval development were presented in Battle (1940).

Figure 13. Cultured (fancy) form of Goldfish; 110 millimeter SL adult purchased from pet store. 

(Photo copyright © Richard T. Bryant.)

Figure 14. Wild (olivaceous) form of Goldfish; 170 millimeter SL adult, from Douglas Reservoir, Tennessee. 

(Photo copyright © Richard T. Bryant.)

Goldfish  21
Ecology

Goldfish may reach 59 cm TL and up to 3.0 kg 

(IGFA, 2001); however, they generally reach only 15-

20 cm TL and weigh 100-300 g (Szczerbowski, 2001). 

Lifespan is typically 6-7 years, but has been reported as 

long as 30 years (Essing, 1898, in Carlander, 1969).

Typical habitat includes the quiet backwaters of 

streams and pools, especially those with submerged 

aquatic vegetation (Hensley and Courtenay, 1980; 

Trautman, 1981; Robison and Buchanan, 1988). 

The Goldfish is tolerant of high levels of turbidity 

(Wallen, 1951), temperature fluctuations (reviewed 

by Spotila and others, 1979), and low levels of 

dissolved oxygen (Zhadin and Gerd, 1963; Walker 

and Johansen, 1977). Laboratory results reported pH 

tolerance levels between 4.5-10.5, and a preference 

for pH levels between 5.5-7.0 (Szczerbowski, 2001). 

Although laboratory tests suggested that eggs and 

fry are not particularly salinity tolerant (Murai and 

Andrews, 1977), the Goldfish is reported to live in 

salt lakes on the coast of the Black Sea and to inhabit 

the floodplain of the Ob delta in Russia (Zhadin and 

Gerd, 1963). The Goldfish has been captured in waters 

with salinities as high as 17 parts per thousand (ppt) 

(Schwartz, 1964), although studies have shown an 

inability to withstand long exposures exceeding 15 ppt 

(Lockley, 1957). Adults thrive equally well in salinities between 0-6 ppt (Canagaratnam, 1959), and can 

survive water temperatures between 0-41 °C (Carlander, 

1969; Moyle, 2002). Additionally, the species is more 

tolerant of aquatic pollution than most native North 

American fishes (Robison and Buchanan, 1988).

The ominvorous diet includes planktonic crustaceans, phytoplankton, insect larvae, fish eggs 

and fry, benthic vegetation, and detritus (Scott 

and Crossman, 1973; Hensley and Courtenay, 

1980; Robison & Buchanan, 1988; Moyle, 2002). 

Foraging Goldfish may create high levels of turbidity, which can result in the decline of aquatic 

vegetation (Richardson and others, 1995).

Native Distribution

The Goldfish is native to Eastern and Central Asia, 

including China, Russia, Korea, and possibly Japan 

and Taiwan (Wheeler, 1978; Szczerbowski, 2001). It 

may also be native to parts of eastern Europe (Raicu 

and others, 1981); however, widespread transfer over 

several centuries has obscured the natural distribution. 

U.S. Introductions

The Goldfish is thought to be the first foreign 

fish species introduced to North America (De Kay 

1842; Courtenay and others, 1984; Fuller and others, 

1999). The first recorded releases in the U.S. probably occurred during the late 1600s (De Kay, 1842; 

Courtenay & Stauffer, 1990), and the species is now 

reported in all states except Alaska (Fuller and others, 

1999). The Goldfish is raised for the aquarium trade 

(as both an ornamental and live food), as bait for 

anglers, and as forage in fish hatcheries. Bait dealers 

in coastal regions along the Gulf of Mexico sometimes sell Goldfish under the names “Black Saltys” 

or “Black Salties.” Although not typically eaten by 

humans in the U.S., it is a valued food fish in China. 

Escapes from aquaculture facilities and deliberate 

releases have resulted in the establishment of localized populations across much of the U.S. The exact 

distribution is difficult to ascertain, as introductions 

continue intermittently throughout much of the country.

22  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Hawaii

REPRODUCINGREPORTEDSTATES WITH RECORDS

EXPLANATION

Goldfish

Carassius auratus

Alaska

Plate 2. Distribution of Goldfish in the United States. See Methods for details regarding data used to create maps, definitions of “reproducing” and “reported” and shading of HUCs and states.

Goldfish  23
Crucian Carp from Denmark. Upper photo 

from Værløse, Denmark; lower photo from 

Danmarks Akvarium (Denmark’s Aquarium), 

Charlottenlund. (Photos copyright © www.

jjphoto.dk, courtesy of Johnny Jensen.)

24  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Crucian Carp

Carassius carassius (Linnaeus 1758)

Similar Species

The long dorsal fin of the Crucian Carp, with a 

strong, serrated spine-like ray followed by 15 or more 

branched rays, distinguishes it from most native North 

American cyprinids, which usually lack the spine-like ray 

and typically have fewer than 11 branched dorsal rays. 

Of the foreign nonindigenous cyprinids, the Crucian 

Carp most closely resembles the Goldfish and Common 

Carp. Crucian Carp is distinguished from Goldfish by its 

slightly convex dorsal-fin margin and slightly emarginate caudal fin; juvenile and young adult Crucian Carp 

have a black spot at the base of the caudal fin. The 

Goldfish has a straight or slightly concave dorsal-fin 

margin, a deeply emarginate caudal fin, and lacks the 

spot at the base of the caudal fin. The typical form of the 

Crucian Carp is slightly deeper bodied than Goldfish.

Denticles on the posterior margin of the spine-like dorsal 

ray are smaller and more numerous in Crucian Carp (28-

29) than in Goldfish (10-11). Crucian Carp lacks barbels, 

which distinguishes it from Common Carp.

Description

The Crucian Carp (fig. 15) is medium-sized 

fish, usually <50 cm TL and 1.8 kg (Wheeler, 1978). 

Maximum size is about 64 cm TL (IGFA, 2001) and 

5 kg (Berg, 1964). Typically, individuals are deepbodied and laterally compressed (fig. 16); however, a 

slender “shallow-bodied” variety also exists (fig. 17). 

The dorsal fin has iii-iv (14-21) rays and a stout, spinelike ray precedes the branched rays. The anal fin has 

ii-iii (5-8) rays. The mouth is terminal and oblique, and 

the peritoneum is pale. The lateral line is complete, 

with 28-37 relatively large scales. The pharyngeal teeth 

are in one row (0,4-4,0; fig. 18). Gill rakers on the first 

arch count 22-33. The body is golden copper, darker 

dorsally, with reddish fins. Sexual dimorphism is not 

pronounced (Szczerbowski and Szczerbowski, 2001). 

Meristics are given in appendix B.

Figure 15. Crucian Carp, UF 30247, 101 millimeter SL, from Yeosu, South Korea.

  25
Figure 16. Deep-bodied form of Crucian Carp. (After Antipa (1909); from Bănărescu (1964); 

reprinted with permission.)

Figure 17. Slender (humilis) form of Crucian Carp. (From Bănărescu (1964); reprinted with permission.)

26  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Variation

Due to ecological factors, such as predatory 

pressure, Crucian Carp varieties can be either deep 

bodied or shallow bodied (Holopainen and others, 1997). 

The typical deep-body form is strongly arched dorsally 

(fig. 16), whereas the shallow-body form, referred to as 

humilis (Bănărescu, 1964), is more fusiform (fig. 17). 

Many of the systematic problems mentioned in our 

account on Goldfish also apply to Crucian Carp.

The Crucian Carp regularly hybridizes with 

Common Carp (Bănărescu, 1964; Berg, 1964; Lin 

and Peter, 1991). An illustration of a hybrid Crucian 

Carp X Common Carp originally published by Antipa 

(1909), appears in Bănărescu (1964, p. 504). Meristics 

of Crucian Carp X Common Carp hybrids are given 

in appendix B. The Crucian Carp also hybridizes with 

Goldfish (Szczerbowski, 2001). Attempts to crossbreed 

Crucian Carp with other cyprinids (including Grass 

Carp, Rudd, and Tench) produced hybrids with high 

levels of mortality (Kasama and Kobayasi, 1989, 1990; 

and Riabov, 1979, in Szczerbowski and Szczerbowski, 

2001). 

Reproduction

Age at sexual maturity varies with environmental 

conditions, with individuals in warmer regions generally 

maturing faster than those in colder ones. Most Crucian 

Carp mature between 2-5 years of age, with males generally maturing a year earlier than females. The species is 

a batch spawner, releasing adhesive eggs over vegetation 

when water temperatures rise above 18 °C (Aho and 

Holopainen, 2000; Szczerbowski and Szczerbowski, 

2001). The eggs are spherical, yellow-orange, and are 

about 1.5 mm in diameter (Laurila and Holopainen, 

1990). The eggs remain attached to vegetation until 

they hatch in about 4 days at 20 °C (Laurila and others, 

1987). The larvae possess an adhesive gland on the 

forehead, which allows them to adhere to submerged 

vegetation until the yolk sac is absorbed about 10 days 

after hatching (Szczerbowski and Szczerbowski, 2001). 

Egg, larval, and juvenile development were described in 

Laurila and Holopainen (1990).

Ecology

The Crucian Carp typically grows to about 50 cm 

TL and 1.8 kg (Wheeler, 1978); however, individuals may attain sizes of up to 64 cm TL (IGFA, 2001) 

and 5 kg (Berg, 1964). The maximum lifespan of wild 

Crucian Carp is about 10 years (Szczerbowski and 

Szczerbowski, 2001). Habitat generally includes shallow, slow-flowing parts of rivers, lakes, and ponds with 

abundant submerged aquatic vegetation. The species is 

capable of inhabiting temporary ponds by burying into 

mud as water levels decrease (sometimes for several 

weeks) until normal water levels become available again 

(Rybkin, 1958, in Szczerbowski and Szczerbowski, 

2001). Predation may significantly alter densities and 

size-structures of populations. A Swedish study showed 

that lakes containing predators often contained high 

densities of shallow-bodied Crucian Carp, whereas 

lakes without predators contained larger, deep-bodied 

individuals (Brönmark and others, 1995; Holopainen and 

others, 1997). The Crucian Carp is a remarkably hardy 

fish. Historical accounts report the species can live for 

hours out of the water, and can survive packaging and 

transport in snow or damp leaves (Seeley, 1886). Like 

Goldfish, the Crucian Carp is tolerant of low-oxygen 

conditions and high turbidity. Survival has been documented at water temperatures below 0 °C, and individuals may even survive for a few days with a frozen 

integument (Szczerbowski and Szczerbowski, 2001). 

The preferred temperature for Crucian Carp was reported 

as 27 °C and the upper lethal temperature was 38.5 °C 

(Hellawell, 1986). The ability to use anaerobic metabolism allows Crucian Carp to survive for several months 

in anoxic water at low temperatures, for example, in 

lakes frozen over with ice (Holopainen and Hyvärinen, 

1984; Piironen and Holopainen, 1986). In their native 

range, feeding may stop for several months as the fish 

rest in a state of “suspended animation” during winter 

months when ponds become anoxic and covered with 

Figure 18. Pharyngeal teeth (0,4-4,0) of Crucian 

Carp, UF 30247, 101 millimeter SL, from Yeosu, 

South Korea.

Crucian Carp  27
ice (Zhadin and Gerd, 1963; Penttinen and Holopainen, 

1992). In addition to depressing cellular energy 

demands, the Crucian Carp was reported to respond to 

anoxia by decreasing its swimming activity by about 

50 percent of that displayed during normoxia (Nilsson 

and others, 1993). Crucian Carp can survive indefinitely 

over a pH range of 4.0-10.5 (Hellawell, 1986). There is 

some evidence that the species is tolerant to low levels 

of salinity. For example, in parts of the former Soviet 

Union, the Crucian Carp inhabits brackish lakes of the 

steppe with salinities to 16 ppt, and spawns in the saline 

Volga River Delta (Zhadin and Gerd, 1963). 

The Crucian Carp is omnivorous (Prejs, 1973), and 

its diet varies seasonally (Penttinen and Holopainen, 

1992). Diet studies report a predominance of cladocerans 

as well as trichopterans, rotifers, ostracods, copepods, 

chironomids, ephemeropterans, nematodes, algae, 

detritus, and plant matter (Prejs, 1973; Penttinen and 

Holopainen, 1992).

Native Distribution

The Crucian Carp is native to Europe and Asia. For 

details of the native range, refer to Szczerbowski and 

Szczerbowski (2001). 

U.S. Introductions

Over the past two centuries, there have been a few 

scattered reports of the occurrence of Crucian Carp 

in the U.S. (possibly involving hybrids with either 

Goldfish or Common Carp). Meek and Hildebrand 

(1910) reported Crucian Carp thriving in the lagoons 

and parks of Chicago. However, a more recent work on 

Illinois fishes (Smith, 1979) suggested this population 

disappeared long ago. There are no recent reports of 

established populations of Crucian Carp in the U.S. An 

earlier report that the species had been introduced into 

Texas (see Fuller and others, 1999) is now considered 

unlikely. Robert Howells (Texas Parks and Wildlife 

Department, personal commun, 2004) believes that the 

species was never introduced into Texas and that earlier 

reports were probably based on Goldfish. Although the 

status of previous introductions is uncertain, fish farmers 

in Arkansas have recently been contacted by commercial 

fish markets about the possibility of culturing the species 

for the live-food fish trade in the U.S. Future importation 

of Crucian Carp may lead to its introduction and possible 

establishment. Consequently, its introduction and status 

remain uncertain. For additional details, refer to Fuller 

and others (1999). 

28  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Hawaii

Crucian Carp

Carassius carassius

Alaska

REPORTEDSTATE WITH RECORDS

EXPLANATION

Plate 3. Distribution of Crucian Carp in the United States. See Methods for details regarding data used to create maps, definition of “reported” and shading of HUCs and states.

Crucian Carp  29
Commercial fisherman with Grass Carp netted from river in 

Louisiana, 2004. (Photo by Rusty Kimble.)

30 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Grass Carp

Ctenopharyngodon idella (Valenciennes 1844)

Description

The Grass Carp (fig. 19) is a large species, often 

reaching over 1 m TL. Maximum size is about 1.5 m TL 

and 45 kg or more (Robison and Buchanan, 1988; Etnier 

and Starnes, 1993; Laird and Page, 1996). The species 

has an oblong body, wide head, and rounded belly. 

The dorsal fin has i-iii (7-8) rays. The anal fin is set far 

to the rear on the body and has ii-iii (8-10) rays. The 

origin of the dorsal fin is anterior to the pelvic-fin base. 

Both dorsal and anal fins are rounded. The caudal fin is 

deeply forked. All fins are soft-rayed. The lateral line is 

complete, with 34-45 scales, and is slightly decurved. 

The mouth is terminal, somewhat oblique, and lacks 

barbels. The eyes are at the approximate level of the 

axis of the body or slightly higher. The gill rakers are 

short, unfused, widely set, and number 12-16 on the first 

arch. The pharyngeal teeth have deep groves, are in two 

rows, and may count 2,5-4,2; 2,4-4,2; or 2,4-5,2 (fig. 20; 

Shireman and Smith, 1983). Scales along the dorsum 

and sides are usually dark-edged, giving a cross-hatched 

effect. Juvenile Grass Carp are silvery (fig. 21). Adults 

are often dark gray along the dorsal surface and brassy 

Figure 19. Grass Carp, SIUC 23044, 289 millimeter SL, from Alexander County, Illinois.

Figure 20. Pharyngeal teeth (2,4-5,2) of Grass Carp, 

SIUC 23044, 289 millimeter SL, from Alexander 

County, Illinois. (Also see to fig. 9, p. 13.)

along the sides of the body (fig. 22). In some situations, 

the species may appear much darker and olivaceous 

on the dorsal surface (fig. 23). The fins are typically 

green-gray to dull silver. Grass Carp meristics are given 

in appendix B. 

  31
Figure 21. Subadult male Grass Carp, 218 millimeter SL, from Lonake Hatchery, Arkansas. 

(Photo by Noel Burkhead.)

Figure 22. Adult Grass Carp, 559 millimeter SL, from Malone Fish Hatchery, Arkansas. 

(Photo copyright © Richard T. Bryant.)

Figure 23. Adult Grass Carp, 455 millimeter SL, from Reelfoot Lake, Tennessee. 

(Photo copyright © Richard T. Bryant.)

32  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Although both sexes may develop breeding 

tubercles, they typically appear only on males. Breeding 

tubercles may occur along the upper surface of the 

pectoral fins, the ridges of the pectoral-fin rays, on the 

first dorsal-fin ray, and over the dorsal surface of the 

caudal peduncle (Opuszynski and Shireman, 1995). 

Similar Species

The Grass Carp can be distinguished from native 

cyprinids by the position of its anal fin, which is set far 

back on the body (fig. 19) and the deep lateral grooves 

in its pharyngeal teeth (fig. 20). Native cyprinids have an 

anal fin that is more anterior than that of the Grass Carp, 

and have pharyngeal teeth that lack deep lateral grooves. 

The Grass Carp closely resembles Black Carp, but 

can be distinguished by its pharyngeal teeth and (in most 

cases) body color. The Grass Carp has long, serrated 

pharyngeal teeth (sometimes with hooks) whereas those 

of adult Black Carp are smooth and molariform. Adult 

Grass Carp are lighter in color than Black Carp, especially the fins. For additional characteristics useful in 

distinguishing Black Carp from Grass Carp, refer to the 

Black Carp species account.

Variation

Concern over ecological impacts in natural systems 

has resulted in widespread use of triploid Grass Carp 

that are presumably sterile (Clugston and Shireman, 

1987). Morphologically, triploids are indistinguishable 

from (fertile) diploids (Bonar and others, 1988). Triploid 

Grass Carp may be produced using heat, pressure, or 

chemical shocking of the fertilized eggs (Clugston and 

Shireman, 1987; Opuszynski and Shireman, 1995). 

However, because most treatments used to create triploid 

Grass Carp are not 100 percent effective, the ploidy of 

each fish must be verified (that is, either diploid, 2n or 

triploid, 3n). Ploidy is typically determined by analysis 

of blood taken from live or freshly killed specimens. The 

preferred technique uses a particle sizer (for example, 

Coulter Counter©) with a channelyzer to estimate ploidy 

by analyzing the distribution of red blood cell nuclear 

volumes (Wattendorf, 1986).

Before widespread use of triploid Grass Carp 

became the main alternative to releasing reproductively 

viable (diploid) individuals, there was limited production 

and release of a sterile hybrid formed by crossing female 

Grass Carp with male Bighead Carp (Fuller and others, 

1999; Nico, 2005). The resulting offspring of this cross 

had closely spaced gill rakers and an abdominal keel 

like the paternal Bighead Carp, as well as pharyngeal 

teeth and an elongated body resembling the maternal 

Grass Carp (Berry and Low, 1970; Verigin and others, 

1975; Kilambi and Zdinak, 1981). Although hybrids 

can allegedly feed on either plankton or macrophytes, 

Kilambi and Zdinak (1982) reported a preference for 

zooplankton. Karyology of the hybrid was given in 

Márián and Krasznai (1978) and Beck and others (1980). 

Kilambi and Zdinak (1981) described the hybrid larvae. 

Meristics for Grass Carp X Bighead hybrids are given in 

appendix B.

Grass Carp have been artificially hybridized with 

Common Carp (Makeyeva and Verigin, 1974a; Stanley 

and Jones, 1976; Avault and Merowsky, 1978), Bighead 

Carp (Andriasheva, 1968; Beck and others, 1980), Silver 

Carp (Andriasheva, 1968) and Black Carp (Makeyeva 

and Verigin, 1993). 

Reproduction

Sexual maturity is reached at an average age of 

2-5 years in subtropical/tropical areas and 4-7 years 

in temperate regions (Alikunhi and Sukumaran, 1964; 

Bardach and others, 1972). Males generally mature a 

year earlier than females (Opuszynski and Shireman, 

1995). Shireman and Smith (1983) reported that 

Grass Carp may mature earlier than these averages. 

For example, mature 1-year old males and 2-year old 

females were documented in tropical India and Malaysia 

(Hickling, 1967). Alternately, maturation can take 9-10 

years in cold climates (Makeeva, 1963, in Hickling, 

1967). The condition of gonads through the stages of 

development was reviewed by Opuszynski and Shireman 

(1995). Fecundity has been found to range widely, from 

255,000-2,000,000 eggs (Vinogradov and others, 1966; 

Gorbach, 1972; Shireman and Smith, 1983; Opuszynski 

and Shireman, 1995), and fecundity reportedly increased 

with age and mass (Gorbach, 1972). Egg and larval 

development were described by Bailey and Boyd (1970) 

and Nakamura (1969). Although Grass Carp spawning commonly occurs in large rivers, Tang (1960a,b) 

reported an unusual instance of a few spawning events 

in a Taiwan reservoir. The success of those particular 

spawning events is uncertain (Nico and others, 2005). 

Krykhtin and Gorbach (1981), who studied the downstream drift of Grass Carp eggs in the Amur Basin, 

determined that spawning occurred at water temperatures between 17- 26 °C, with peak activity at 21-26 °C. 

Stanley and others (1978) reviewed literature from Asia 

and Europe on requirements for spawning, including 

temperature, water level fluctuation, and spawning site 

characteristics.

Grass Carp  33
Spawning Requirements

of Chinese Carps

 In general, the four species of Chinese carps require large riverine 

environments for successful reproduction (Nico and others, 2005). Both migration 

and spawning activities are initiated in response to a combination of physical and 

hydrologic changes, such as increasing water levels, flows, and water temperature 

(Yih and Liang, 1964; Jennings, 1988; Opuszynski and Shireman, 1995). However, 

the importance of any one factor may vary among different regions (Nico and 

others, 2005). 

 Spawning grounds are usually located in river reaches characterized by 

turbulent or whirlpool-like flow, often in the vicinity of islands or stream junctions 

(Yih and Liang, 1964; Nico and others, 2005). Reported current velocities of 

spawning areas in China ranged from 0.33-0.90 m/s with temperatures ranges of 

19.2-29.0 °C (Yih and Liang, 1964). 

 The appropriate environment, particularly with regard to water turbulence 

and higher water temperatures, is considered critical because it apparently 

stimulates spawning and is necessary for successful early development of eggs 

(Nico and others, 2005). The eggs of Chinese carps are semibuoyant and are carried 

by currents until they hatch (Soin and Sukhanova, 1972). 

 Introduced populations have been known to successfully reproduce in 

artificial canals of sufficient length that somewhat mimic the flow of natural rivers, 

such as the Kara Kum Canal in Turkmenistan (Aliyev, 1976; Nico and others, 

2005). Eggs or larvae of Chinese carps found in reservoirs suggest the possibility 

of spawning in these habitats (Tang, 1960a,b). Nevertheless, uncertainty remains as 

to whether spawning occurred within the reservoir or in a connected stream (Nico 

and others, 2005). If spawning does occur in such artificial habitats, it could have 

been triggered by fluctuations in water levels or wave actions that mimicked natural 

riverine environments. 

(Silver, Grass, Bighead, and Black Carps)

34  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Silver Carp

Grass Carp

Bighead Carp

Black Carp

  35
Ecology

The Grass Carp is a large species that can attain a 

weight of 45 kg (Robison and Buchanan, 1988; Etnier 

and Starnes, 1993) and a length of 1.5 m TL (Laird 

and Page, 1996). Typical longevity is about 5-11 years 

(Berg, 1964), but an individual in the Amur River was 

estimated to be 21 years, based on scale growth rings 

(Gorbach, 1961). Growth is relatively rapid, especially in 

the tropics where it can average 10 g per day (Hickling, 

1967). 

Typical habitat includes quiet waters, such as lakes, 

ponds, pools, and backwaters of large rivers, and individuals generally do not travel long distances except for 

the annual spawning migration (Mitzner, 1978; Nixon 

and Miller, 1978; Bain and others, 1990). Nevertheless, 

there are reports of juvenile Grass Carp traveling as 

far as 1,000 km from their original spawning grounds 

(Stanley and others, 1978). Shallow water is the generally preferred habitat, although deeper waters are used 

when temperatures decrease (Nixon and Miller, 1978). 

A number of experimental studies have reported environmental tolerances for Grass Carp. Fry and fingerlings 

have been reported to tolerate water temperatures from 

0-40 °C (Stevenson, 1965; Vovk, 1979), and Stevenson 

(1965) reported that fingerlings in small ponds in 

Arkansas survived 5 months under heavy ice cover. 

Chilton and Muoneke (1992) reported an upper lethal 

temperature range for fry as 33-41 °C, and for yearlings 

as 35-36 °C. Bettoli and others (1985) documented a 

thermal maximum of 39.3 °C and a preferred temperature of 25.3 °C. Collee and others (1978) reported that 

feeding declined sharply below 14 °C. Nico and others 

(2005) reviewed temperature tolerance of Grass Carp 

and the other Chinese carps.

Oxygen consumption (per gram of body 

mass) increases with higher water temperature and 

decreases with fish age and mass (Chen and Shih, 

1955; Woźniewski and Opuszynski, 1988). The 

lethal low oxygen level for juveniles was <0.5 mg/L 

(Negonovskaya and Rudenko, 1974). The maximum 

pH for culture of Grass Carp was reported as 9.24 

(Liang and Wang, 1993). Egg hatching was delayed 

below pH 6.5 and increased mortality and deformation 

of larvae occurred below pH 6.0 (Li and Zhang, 1992). 

Sensitivity to low pH decreased with age (Li and Zhang, 

1992). Median lethal concentration of ammonia was 

determined to be 1.05 mg/L (Gulyás and Fleit, 1990).

The Grass Carp appears to be tolerant of low levels 

of salinity, and may occasionally enter brackish-water 

areas. Fry (32-50 mm TL) survived transfer from freshwater to a salinity of 12 ppt (Chervinski, 1977). Adults 

(2+ years) survived 10.5 ppt salinity for about 24 days 

and 17.5 ppt for 5 hours (Cross, 1970). However, Grass 

Carp acclimated to 3, 5, and 7 ppt had an upper tolerance 

of about 14 ppt (Kilambi and Zdinak, 1980). Maceina 

and Shireman (1980) showed that fingerlings reduce 

feeding at 9 ppt and stop feeding altogether at 12 ppt; 

thus, they predicted Grass Carp could inhabit brackishwater bodies up to 9 ppt. Maceina and Shireman (1979) 

reported that the species can tolerate 14 ppt for as long 

as 4 days, but that the upper long-term tolerance of 

fingerlings to saline waters was lower, about 10-14 ppt. 

Maceina and others (1980) noted that oxygen consumption decreased along a salinity gradient of 0-9 ppt. 

Movement of Grass Carp from one river to another 

through a brackish-water estuary (Pavlov and Nelovkin, 

1963, in Cross, 1970) is not surprising given the species’ 

tolerance to low levels of salinity. Avault and Merowsky 

(1978) reported food preference and salinity tolerance of 

hybrid Common Carp X Grass Carp. 

The species is probably best known for its ravenous appetite for plant matter (especially macrophytes); 

however, small Grass Carp feed on invertebrates before 

switching to plants. Watkins and others (1981) reported 

that Grass Carp larvae consumed benthic invertebrates 

(primarily chironomid larvae) and zooplankton until they 

reach about 55 mm TL. Edwards (1973) reported age-0 

Grass Carp consumed oligochaetes, mayflies, caddisflies, amphipods, and chironomids. Fry of Rainbow 

Trout (Oncorhynchus mykiss) and Common Carp were 

eaten by young Grass Carp (even in the presence of 

preferred plants), but Grass Carp would not eat the eggs 

of either species (Edwards, 1973; Singh and others, 

1976). Grass Carp larger than 25 cm did not feed on 

fry in the laboratory (Singh and others, 1976). The size 

at which Grass Carp begins to feed on plants depends 

on temperature, with smaller fish switching to plants 

in warmer waters (Stanley and others, 1978). Adults 

feed on a variety of aquatic macrophytes, such as water 

hyacinth (Eichhornia crassipes), eelgrass (Vallisneria 

americana), cattails (Typha spp.), and Hydrilla spp. 

(Collee and others, 1978; reviewed in Opuszynski and 

Shireman, 1995; Cassani, 1996). In some cases, Grass 

Carp will consume animals when plant material is lacking (Nikol’skiy and Aliyev, 1974; Forester and Avault, 

1978). Alternatively, Grass Carp may consume terrestrial macrophytes in the absence of aquatic vegetation 

(Kilgen and Smitherman, 1971; Terrell and Fox, 1974). 

Kilgen and Smitherman (1971) reported that individuals 

raised their heads clear of the water to consume terrestrial macrophytes. The species is a voracious herbivore 

36  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
that can quickly eliminate large volumes of vegetation 

(Mitzner, 1978). Although some reports indicated that 

removal of aquatic vegetation by Grass Carp was advantageous for some game fishes (for example, Maceina 

and others, 1991), such habitat modification could result 

in habitat loss for native fishes, birds, and invertebrates 

(Gasaway and Drda, 1977; Forester and Avault, 1978; 

Ware and Gasaway, 1978; Laird and Page, 1996; Ross, 

2001).

Native Distribution

The Grass Carp is native to rivers of eastern Asia, 

from the Amur River of far eastern Russia and China, 

south to the West River of southern China (Shireman and 

Smith, 1983; Li and Fang, 1990).

U.S. Introductions

The Grass Carp was first brought into the U.S. in 

1963, when it was imported by aquaculture facilities 

in Alabama and Arkansas. Subsequently, it was widely 

stocked for vegetation control (Courtenay and others, 

1984; Fuller and others, 1999). Escapes from aquaculture facilities, intentional stocking (both legal and 

illegal), and movement of introduced populations have 

expanded its range. The species is now known from 

almost every state, and is established in the Mississippi, 

Missouri, and Ohio rivers, as well as the smaller Trinity 

River (Texas).

Grass Carp  37
Ha

waii

REPRODUCINGREPORTEDSTATES WITH RECORDS

EXPLANATION

Grass Car

p

Ctenopharyngodon idella

Alaska

Plate 4. Distribution of Grass Carp in the United States. See Methods for details regarding data used to create maps, definitions of “reproducing” and “reported” and shading of HUCs and states.

38  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Common Carp

Cyprinus carpio Linnaeus 1758

Shortly before and during spawning, mature males 

(and some females) develop breeding tubercles (appearing as small granules). In males, the tubercles appear 

primarily on the opercle, pre-opercle, and under the 

eyes, although they may also be present elsewhere on 

Description

The Common Carp (fig. 24) is a large species, 

reaching lengths of over 1 m (Berg, 1964). The maximum reported weight is 37.3 kg (IGFA, 2001). The body 

is wide, elongated, and torpedo-shaped. The scales are 

large, and number 32-40 along the lateral line. The body 

is slightly arched anterior to the dorsal fin. The long 

dorsal fin has ii-iv (15-23) rays that include a strong, 

serrated spine-like ray followed by 15 or more branched 

rays. The anal fin has ii-iv (4-6) rays. The caudal fin is 

moderately forked. The mouth is subterminal with two 

barbels on each side. The eyes are set high on the head. 

The pharyngeal teeth are molariform and those in the 

main row are heavy with flattened grinding surfaces. The 

pharyngeal tooth formula is 1,1,3-3,1,1 (in three rows; 

fig. 25). Total gill rakers on the first arch number 18-36. 

The Common Carp is generally brassy to yellowish, with 

lower fins often yellow-orange; however, ornamental 

forms exhibit a wide range of bright colors (see section 

on variation, below). Meristics are given in appendix B.

Figure 24. Common Carp, SIUC 42681, 120 millimeter SL, from Lake County, Illinois.

Figure 25. Pharyngeal teeth (1,1,3-3,1,1) of Common 

Carp, SIUC 42681, 120 millimeter SL, from Lake 

County, Illinois. (Also see fig. 3, p. 8.)

  39
the head, caudal peduncle, fin rays, and the scales below 

(less frequently above) the lateral line (Balon, 1995; 

Baruš and others, 2001). When present on females, 

breeding tubercles only occur on the head (Balon, 1995). 

Coad (2005) indicated that females are deeper-bodied 

than males, and also noted sexual differences in fin 

height and length.

Similar Species

The long dorsal fin includes a strong, serrated spinelike ray followed by 15 or more branched rays. This 

characteristic distinguishes it from most native North 

American cyprinids, which typically have fewer than 

11 rays and usually lack the spine-like ray. 

The Common Carp has two barbels on each side of 

the head near the posterior end of the upper jaw. This 

characteristic distinguishes it from Crucian Carp and 

Goldfish, which lack barbels. Gerlach (1983) listed 

characteristics that distinguish the larvae of Goldfish 

from the Common Carp.

Variation

A wide geographic range in combination with a 

long history of culture and artificial selection has given 

rise to a number of varieties of Common Carp. Thus, the 

species exhibits a wide variation in meristic and morphological characteristics (appendix B). Baruš and others 

(2001) recognized and provided a key for three subspecies: Cyprinus carpio carpio (European and Central 

Asian Common Wild Carp), Cyprinus carpio haematopterus (East Asian Common Wild Carp), and Cyprinus 

carpio viridiviolaceus (Southeast Asian Wild Carp). 

The number, size, and coverage of scales is variable, 

especially among domesticated groups. Based on scale 

patterns, at least four basic forms of Common Carp are 

recognized (Brylinska, 1986, in Baruš and others, 2001). 

However, common names associated with these forms 

are sometimes inconsistently applied (for example, Tave, 

1988; Howells, 1999):

1. Scaled Carp with regular, imbricating scales 

over the entire body, much like the ancestral wild 

Common Carp. The large, cycloid scales of the 

Scaled Carp are pigmented along their posterior 

edges, producing a reticulated effect (fig. 26);

2. Mirror Carp with irregular rows of very large 

scales (fig. 27);

3. Leather or Naked Carp either with no scales or 

few, very large scales (fig. 28).

4. Line Carp with a regular single mid-lateral row 

of scales and elsewhere none or only a few scales 

(not illustrated);

Coloration is highly variable. Wild strains are 

generally brassy to yellowish, with lower fins often 

yellow-orange; however, considerable variation occurs 

among cultured varieties. Nishikigoi ornamental carp 

strains (popularly called “Koi”) were developed in Japan 

over the last two centuries (Balon, 1995), and may be 

red, white, gold, black or variegated (fig. 29). 

Natural hybrids of the wild Common Carp and the 

Crucian Carp are often found where the two species 

co-occur (Bănărescu, 1964; Berg, 1964; Lin and Peter, 

1991; see appendix B for meristics). The Common 

Carp naturally hybridizes with Goldfish both in native 

regions, such as Romania (Bănărescu, 1964) and the 

Czech Republic (Prokeš and Baruš, 1996) and where 

they are introduced, such as Canada (Taylor and Mahon, 

1977), Australia (Hume and others, 1983), and Ohio 

(Trautman, 1981). Meristics for Common Carp X 

Goldfish hybrids are given in appendix B. Common 

Carp has been artificially hybridized with Grass Carp 

(Makeyeva and Verigin, 1974a; Stanley and Jones, 1976; 

Avault and Merowsky, 1978), Bighead Carp (Makeyeva, 

1968, 1972; Verigin and Makeeva, 1974), Silver Carp 

(Makeyeva, 1968; Makeyeva and Verigin, 1974b), and 

Tench (Victorovsky, 1966). Crossbreeding of Common 

Carp with other cyprinids is reviewed in Schwartz (1972, 

1981). The Common Carp is not known to hybridize 

with any cyprinids native to North America. 

Reproduction

Males first spawn at an age of about 3 years, after 

attaining a length of 36 cm SL and weight of 1 kg 

(Berg, 1964). Maximum fecundity has been estimated 

from 2–7 million eggs (Baruš and others, 2001; Moyle, 

2002; Coad, 2005). The Common Carp is a batch 

spawner (Balon, 1995), releasing its adhesive eggs 

over vegetation. Reported minimum temperatures for 

commencement of spawning vary (10-12 °C, Berg, 

1964; 13-16 °C, Bănărescu, 1964; 16.5 °C, Lubinski and 

others, 1986; 18 °C, Balon, 1995). In its native range, 

the species reportedly prefers to spawn during periods of 

high water over freshly flooded meadows at sites where 

the water depth is 25-50 cm (Berg, 1964; Balon, 1995). 

Wild carp have also been reported to spawn along the 

coasts of islands situated in lakes (Kazancheev, 1981, 

in Baruš and others, 2001), and in estuaries along the 

coastline where the water is shallow and aquatic plants 

40 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Figure 26. Common Carp (Scaled variety), 272 millimeter SL, from Lake County, Tennessee. 

(Photo copyright © Richard T. Bryant.)

Figure 27. Common Carp (Mirror variety), 310 millimeter SL, from Knox County, Tennessee. 

(Photo copyright © Richard T. Bryant.)

Figure 28. Common Carp (Leather variety). (Bulletin of the U.S. Fish Commission, 1890.)

Common Carp  41
are numerous (Baruš and others, 2001). Berg (1964) 

recorded Common Carp spawning along the coast of 

the Aral Sea in salinities as high as 10 ppt. At 20 °C, 

eggs hatch 3-4 days after fertilization (Balon, 1995). 

Larval development was described in Balon (1995) and 

Nakamura (1969), and egg and larval development were 

described and illustrated in Jones and others (1978). 

Ecology

The Common Carp is a large species, reaching 

lengths of over 1 m (Berg, 1964). The largest known 

specimen captured to date was a 37.3 kg individual taken 

in Romania (IGFA, 2001). The species is long-lived, 

frequently attaining an age of 15 years, and sometimes 

living much longer. For example, a 50-year old wild carp 

was captured in England (Panek, 1987) and a 47-year 

old captive individual was reported by Flowers (1935, 

in Carlander, 1969). Misinterpretation of scale circuli is 

responsible for the erroneous legend (that persisted for 

over a century) that Common Carp could attain ages of 

100 or even 200 years.

The Common Carp is found in a wide variety 

of habitats. Baruš and others (2001) reported that in 

the Danube River the preferred habitat included lotic 

stretches of the river with mud and sand substrates and 

abundant submerged aquatic vegetation. Common Carp 

in the Danube River also used oxbow lakes and other 

water bodies along the floodplain, such as inundated 

meadows. The species generally inhabits lakes, ponds, 

and the lower sections of rivers (usually with moderately 

flowing or standing water), but is also known from 

brackish-water estuaries, backwaters, and bays (Baruš 

and others, 2001). In its native range, the species occurs 

in coastal areas of the Caspian and Aral Seas (Berg, 

1964; Kazancheev, 1981, in Baruš and others, 2001) 

as well as the estuaries of large Ukrainian and Russian 

rivers. Crivelli (1981) reported that the Common Carp 

occurred in brackish-water marshes with salinities up 

to 14 ppt in southern France. In North America, the 

Common Carp inhabits brackish and saline coastal 

waters of several states bordering the Atlantic and 

Pacific Oceans and Gulf of Mexico (Schwartz, 1964; 

Moyle, 2002) as well as the Atlantic and Pacific coasts 

of Canada (McCrimmon, 1968). It has been captured in 

U.S. waters with salinities as high as 17.6 ppt (Schwartz, 

1964). In the U.S., the Common Carp is more abundant 

in manmade impoundments, lakes, and turbid sluggish 

streams receiving sewage or agricultural runoff, and 

less abundant in clear waters or streams with a high 

Figure 29. Koi in a pond at Lí Yuán Garden, Suzhou, People’s Republic of China, October 2004. Koi, an 

ornamental form of Common Carp (Cyprinus carpio), has been selectively bred for its array of colors over the 

past few hundred years by the Japanese. (Photograph by Leo G. Nico.)

42  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
gradient (Pflieger, 1975; Trautman, 1981; Ross, 2001; 

Boschung and Mayden, 2004). Pflieger (1975) noted that 

the Common Carp tends to concentrate in large numbers 

where cannery or slaughter-house wastes are emptied 

into streams.

The species is tolerant to a wide range of environmental conditions. It is somewhat puzzling that although 

the Common Carp has been reported from estuarine and 

marine regions in Europe, Asia, and North America, 

laboratory experiments generally report limited salinity 

tolerance. Upper tolerance limits have been reported 

as 6 ppt for young and 4.5 ppt for eggs (Nakamura, 

1948, in McCrimmon, 1968). Panek (1987) reported 

that salinities of 1.5-2 ppt were lethal in 1.5 days, 

although it is unclear whether this study was conducted 

on adults or juveniles. Wang and others (1997) reported 

that fingerlings could withstand salinities of 10.5 ppt; 

however, growth rates at salinities >3 ppt were half those 

reported for waters with <2.5 ppt salinity. Laboratory 

studies reported decreased oxygen consumption and 

standard metabolism at 3 ppt salinity, as less energy 

was needed to maintain internal equilibrium (Qui Deyi 

and Qin Kejing, in Wang and others, 1997). Common 

Carp <50 days old were tolerant of temperatures 14-

43 °C (Lirski and Opuszynski, 1988a,b). Opuszynski 

and others (1989) reported an upper lethal limit of 43 or 

46 °C (depending on the method of calculation) and an 

optimum growth temperature for juveniles at 38 °C. Pitt 

and others (1956) reported a temperature preferendum 

of 32 °C. The Common Carp is reported to be extremely 

tolerant to turbidity (Panek, 1987). In a laboratory study, 

lethal low oxygen concentration varied from about 

1.3-0.7 mg/L, and decreased with fish age and weight 

(Woźniewski and Opuszynski, 1988). Median lethal 

concentration of ammonia was determined as 0.5 mg/L 

(Gulyás and Fleit, 1990).

Larval Common Carp feed primarily on zooplankton. In its native range, juveniles and adults feed on 

benthic organisms (for example, chironomids, gastropods, and other larval insects), vegetation, detritus, 

and plankton (for example, cladocerans, copepods, 

amphipods, mysids). Feeding habits are similar in the 

U.S., where the diet is composed of organic detritus 

(primarily of plant origin), chironomids, small crustaceans, and gastropods (Summerfelt and others, 1971; 

Eder and Carlson, 1977; Panek, 1987). The Common 

Carp is very active when feeding and its movements 

often disturb sediments and increase turbidity, causing 

serious problems in some regions especially where the 

species is abundant. The species also retards the growth 

of submerged aquatic vegetation by feeding on and 

uprooting plants (King and Hunt, 1967). Silt resuspension and uprooting of aquatic plants caused by feeding 

activities can disturb spawning and nursery areas of 

native fishes (Ross, 2001) as well as disrupt feeding 

of sight-oriented predators, such as bass and sunfish 

(Panek, 1987).

Native Distribution

The Common Carp is native to temperate Eurasia. 

The precise boundaries of the native range are obscured 

by a long history of transplantation by humans (see 

Balon, 1995 and Baruš and others, 2001). The species 

has been an important food item for humans since 

ancient times. The remains of Common Carp have been 

found in archaeological excavations of early human 

settlements (Balon, 1995), and the species was well 

known to the ancient Romans. The Common Carp has 

been raised for thousands of years in Europe and China 

(Balon, 1995). 

U.S. Introductions

The Common Carp is the leading aquaculture 

species in many countries and also an important sport 

fish (Baruš and others, 2001). The species has been 

extensively transferred and now occupies every continent except Antarctica. Considering its importance in 

the Old World, it is no surprise that it has been widely 

introduced throughout the U.S. (beginning as early 

as 1831; Fuller and others, 1999). Common Carp is 

currently thought to be reproducing in all states except 

Alaska. The expanded range of Common Carp in the 

U.S. has occurred via numerous sources, including 

intentional stocking as food fish and ornamentals (for 

example, Koi), escapes from aquaculture facilities, 

use of juveniles as bait fish, and invasions of adjacent 

water-bodies by existing populations. Also, because the 

species is tolerant of brackish waters, there is increased 

likelihood that the Common Carp is capable of migrating 

through estuaries into adjacent coastal streams (Swift 

and others, 1977). 

Common Carp  43
Ha

waii

REPRODUCINGSTATES WITH RECORDS

EXPLANATION

Common Car

p

Cyprinus carpio

Alaska

Plate 5. Distribution of Common Carp in the United States. See Methods for details regarding data used to create maps, definition of “reproducing” and shading of HUCs and states.

44  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Silver Carp

Hypophthalmichthys molitrix (Valenciennes 1844)

Description

The Silver Carp (fig. 30) is a large fish; individuals have been reported to reach about 1.3 m (Xie Ping, 

2003) and weigh over 35 kg (Li and Mathias, 1994). 

The species is deep bodied and laterally compressed, 

with a ventral keel that extends forward from the anus 

almost to the junction of the gill membranes (fig. 31). 

The lateral line is complete and curved ventrally with 

91-124 small scales. The eyes are large and located 

low on the head. The mouth is large, terminal, and 

somewhat oblique. The first gill arch has more than 

100 gill rakers. The rakers are thin, branched, and 

fused into a sponge-like apparatus. The pharyngeal 

teeth are in one row (0,4-4,0) with striated surfaces 

(fig. 32). Barbels are absent. The dorsal fin is short 

with ii-iii (7) rays and lacks a thick spine-like ray. The 

anal fin has ii-iii (11-14) rays. The dorsal surface of 

the body is olivaceous to grayish black and the sides 

are silvery (figs. 33 and 34). Meristics for Silver Carp 

are given in appendix B. 

Figure 30. Silver Carp, SIUC 35334, 204 millimeter SL, from New Madrid County, Missouri.

Figure 31. Ventral keel of Silver Carp.

(Also see to fig. 6, p. 10.)

  45
Silver Carp fingerlings exhibit an unusual morphological adaptation to low oxygen conditions. Adámek 

and Groch (1993) report that hypertrophy of the lower 

lip of Silver Carp fingerlings can appear within 24-48 

hours of oxygen depletion. This rapid morphological 

adaptation serves to increase intake of the surface-water 

layer, and disappears within 24 hours after the return of 

normoxia.

Sexual dimorphism in Silver Carp is subtle. Both 

sexes develop fine tubercles along anterior pectoralfin rays; however, in females these tubercles are only 

present on the distal half of the rays (Opuszynski and 

Shireman, 1995).

Similar Species

Presence of a ventral keel differentiates the 

Silver Carp and Bighead Carp from all native 

cyprinids except the Golden Shiner (Notemigonus 

Figure 32. Pharyngeal teeth (0,4-4,0) of Silver Carp, 

SIUC 35334, 204 millimeter SL, from New Madrid 

County, Missouri.

Figure 33. Juvenile Silver Carp, 130 millimeter SL, from Malone Fish Hatchery, Lonoke County, Arkansas. 

(Photo copyright © Richard T. Bryant.)

Figure 34. Adult Silver Carp, 438 millimeter SL, from the U.S. Fish and Wildlife Service Fish Hatchery, Stuttgart, 

Lonoke County, Arkansas. Reddish color of fins in this photograph is a result of bruising during capture and handling. 

(Photo copyright © Richard T. Bryant.)

46  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
crysoleucas). The Golden Shiner has larger and 

fewer lateral-line scales (39-51) than Silver Carp 

and Bighead Carp (>60). Additionally, the Golden 

Shiner typically has five pharyngeal teeth per side 

(in a single row), whereas Silver Carp and Bighead 

Carp have only four teeth in a single row (per side). 

Small juvenile Silver Carp may resemble native shad 

(family Clupeidae), but can be differentiated by the 

presence of a lateral line and usually <14 anal rays 

(versus no lateral line and >16 anal rays in shad). 

Silver Carp is most similar to Bighead Carp; 

however, it has silvery sides in contrast to the mottled 

sides of the adult Bighead Carp. Additionally, the Silver 

Carp has long, thin gill rakers that are fused to form 

a sponge-like apparatus (fig. 7a in Key) and a ventral 

keel that extends from the anus to the anterior part of 

the breast, almost to the junction of the gill membranes 

(fig. 31). The Bighead Carp has long, thin gill rakers 

that are not fused and has a keel that extends forward 

only to the base of the pelvic fins. When apressed (held 

flat against the body), the pectoral fin of the Silver Carp 

does not extend to the base of the pelvic fins, whereas 

the pectoral fin of the Bighead Carp extends beyond the 

pelvic-fin origin. Typically, the eyes of the Bighead Carp 

are slightly lower on the head than those of the Silver 

Carp; however, this characteristic may not be diagnostic. 

The name “Bigheaded Carps” is often applied 

collectively to include all the Hypophthalmichthys

species. For example, in some publications the Hypophthalmichthys molitrix is referred to as “Bighead Carp.”

Variation

A closely related species, the Largescale Silver 

Carp (Hypophthalmichthys harmandi; Sauvage 1884)

occurs in Hainan Island, China, and northern Vietnam 

(PRFRI, 1991; Chen, 1998). The Largescale Silver Carp 

was previously treated as a subspecies of Silver Carp 

(H. molitrix harmandi; Yen, 1985), but it is now considered a distinct species. Largescale Silver Carp has fewer 

lateral-line scales (78-88) than Silver Carp and more 

anal rays (15). To date, we are unaware of the occurrence 

of Largescale Silver Carp in the U.S.

Silver Carp has been artificially hybridized with 

Common Carp (Makeyeva, 1968, 1975; Makeyeva 

and Verigin, 1974b) and Grass Carp (Andriasheva, 

1968). Silver Carp is also reported to hybridize with 

Bighead Carp both naturally (Verigin and others, 

1979) and through artificial means (Tang, 1965; 

Green and Smitherman, 1984). Larval development 

of Silver Carp X Bighead Carp hybrids was described 

by Mihai-Bardan (1980). Silver Carp is not known to 

hybridize with any native North American cyprinid 

species. The common name “Bighead” is used in this 

report to refer to Hypophthalmichthys molitrix. 

Reproduction

Male Silver Carp attain maturity at 2-3 years in 

subtropical/tropical locales and 4-6 years in temperate 

regions (Alikunhi and Sukumaran, 1964; Kuronuma, 

1968; Bardach and others, 1972; Abdusamadov, 

1987). Males generally mature a year before females 

(Abdusamadov, 1987; Opuszynski and Shireman, 1995). 

Opuszynski and Shireman (1995) reviewed gonad 

condition through the stages of development. Fecundity 

is generally high, and differs among geographic regions 

and fish ages and sizes. Larger Silver Carp tend to have 

more eggs and heavier ovary masses (Verigin and others, 

1990). Fecundity ranges from about 265,000-2,000,000 

eggs per fish (Abdusamadov, 1987; Vinogradov and 

others, 1966; Kamilov and Komrakova, 1999). Egg and 

larval development were illustrated in Nakamura (1969) 

and Soin and Sukhanova (1972).

Krykhtin and Gorbach (1981) studied the downstream drift of Silver Carp eggs in the Amur River Basin 

of eastern Asia, and determined that spawning occurred 

at water temperatures between 17-26.5 °C, with peak 

activity at 21-26 °C. For additional information on 

spawning requirements of Silver Carp, see the section 

entitled “Spawning requirements of Chinese carps” in 

the Grass Carp account. 

Ecology

The Silver Carp is a large fish than can attain a 

maximum length of over 1 meter and a weight of over 

35 kg (Li and Mathias, 1994; Xie Ping, 2003). It is a 

relatively long-lived species, estimated to attain an age 

of 20 years (Berg, 1964). In its native range, Silver Carp 

occurs in large rivers, although the species has been 

stocked in a variety of habitats, including warm-water 

lakes, fish ponds, and impoundments (Berg, 1964; 

Abdusmadov, 1987; Fuller and others, 1999; Xie Ping, 

2003). The Silver Carp is an active fish that typically 

swims in the upper water layer. If disturbed, individuals 

will sometimes leap clear of the water. The sound of an 

outboard motor often causes the Silver Carp to leap out 

of the water and collide with boaters, causing serious 

property damage and human injury. This behavior has 

received considerable attention in the U.S. (Perea, 2002). 

Silver Carp  47
Oxygen consumption (per gram of body mass) has 

been shown to increase with higher water temperature 

and decrease with fish age and mass (Chen and Shih, 

1955; Woźniewski and Opuszynski, 1988). In about 21 

days, larvae are tolerant of oxygen conditions as low 

as 0.5 mg/L (Woźniewski and Opuszynski, 1988). Rai 

(2000) reported growth at pH 7.1-9.7. Liang and Wang 

(1993) reported the maximum pH for culture was 9.24. 

Egg hatching was delayed below pH 6.5, and increased 

mortality and deformation of larvae occurred below 

pH 6.0 (Li and Zhang, 1992). However, sensitivity to 

low pH decreased with age (Li and Zhang, 1992). Vovk 

(1979) reported a temperature tolerance of 0-40 °C. 

Opuszynski and others (1989) reported an upper lethal 

limit of 43.5 or 46.5 °C (depending on the method of 

calculation) and an optimum growth temperature of 

39 °C for juveniles. Data on salinity tolerance is difficult to interpret. Authors have reported that Silver Carp 

cannot tolerate salinities >4 ppt (Waller, 1985; Zang and 

others, 1989), although larvae are known to migrate to 

brackish-water areas of the Caspian Sea where salinities range from 6-12 ppt (Abdusamadov, 1987). Both 

oxygen consumption and standard metabolism decrease 

at 3-4 ppt salinity, as less energy is needed to maintain 

internal equilibrium (von Oertzen, 1985).

The fused gill rakers are used to sieve plankton 

from the water column. Once ingested, food is ground 

against a cartilaginous plate by blunt pharyngeal teeth 

(Robison and Buchanan, 1988). Larvae feed primarily on zooplankton (Korniyenko, 1971; Nikol’skiy and 

Aliyev, 1974). Adults feed primarily on phytoplankton 

and to a lesser extent on zooplankton and detritus 

(Berg, 1964; Nikol’skiy and Aliyev, 1974; Cremer and 

Smitherman, 1980; Burke and others, 1986; Dong and 

Li, 1994). A primary goal of Silver Carp culture is the 

improvement of water quality by reduction of phytoplankton populations. However, the efficacy of this 

species for controlling phytoplankton is controversial 

(Domaizon and Devaux, 1999). Some researchers have 

reported that the introduction of Silver Carp has resulted 

in increased water quality (Kajak and others, 1975, in

Lazzarro, 1987; Leventer, 1979) and, specifically, reductions in blue-green algae (Vovk, 1979; Starling, 1993). 

Conversely, other researchers have reported that the 

presence of Silver Carp increased algal biomass (Burke 

and others, 1986; Laws and Weisburd, 1990).

Native Distribution

The Silver Carp is native to large lowland rivers of 

eastern China (Berg, 1964; Li and Fang, 1990).

U.S. Introductions

The Silver Carp was first introduced to the U.S. in 

1973 for the purpose of controlling plankton blooms in 

catfish-production ponds and sewage lagoons (Freeze 

and Henderson, 1982; Fuller and others, 1999). The 

species was subsequently raised in government and 

private aquaculture facilities. By 1980, specimens were 

found in natural waters, probably the result of escapes 

from aquaculture facilities (Freeze and Henderson, 

1982). Subsequent escapes and contamination of Grass 

Carp stocking with Silver Carp may have contributed 

to the expansion of the species’ range (reviewed in 

Fuller and others, 1999). Silver Carp is now reported 

in 16 states and is established in the middle and lower 

Mississippi River Basin.

48  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Hawaii

REPRODUCINGREPORTEDSTATES WITH RECORDS

EXPLANATION

Silver Carp

Hypophthalmichthys molitrix

Alaska

Plate 6. Distribution of Silver Carp in the United States. See Methods for details regarding data used to create maps, definitions of “reproducing” and “reported” and shading of HUCs and states.

Silver Carp  49
50 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to Their Identification

Commericial fisherman in Louisiana hauling in hoop net full of Bighead 

Carp, 2004. (Photo courtesy of Cathy Mohilo and Rusty Kimble.) 
Bighead Carp

Hypophthalmichthys nobilis (Richardson 1845)

Description

The Bighead Carp (fig. 35; previously known as 

Aristichthys nobilis) is a large species that may grow 

larger than 1 meter TL and weigh up to 40 kg in as 

little as 9 years (Baltagi, 1979, in Jennings, 1988). It is 

deep-bodied and laterally compressed with a smooth 

keel that runs from the anus to near the base of the pelvic 

fins (fig. 36). The lateral line is complete with 91-120 

scales and curved ventrally. The head is large (usually 

>1/3 the SL). Eyes are forward on the head and positioned ventrally. The mouth is terminal and large, with 

the lower jaw slightly longer than the upper one. The 

premaxillary and mandible form bony, rigid lips. Barbels 

are absent. The pharyngeal teeth are moderately long, 

bluntly rounded, and arranged in a single row (0,4-4,0; 

fig. 37). The gill rakers are long and thin, and number 

about 130 on the first arch. The numerous gill rakers 

are closely arranged with membranous septa, but are 

unfused. The dorsal fin is short, lacks a spine-like ray, 

and has ii-iii (7-10) rays. The dorsal-fin origin is posterior to the origin of the pelvic fins. The anal fin has ii-iii 

Figure 35. Bighead Carp, SIUC 23919, 207 millimeter SL, from Washington County, Illinois.

Figure 36. Ventral keel of Bighead Carp.

(Also see to fig. 6, p. 10.)

  51
(10-17) rays. Coloration is dark gray dorsally, fading to 

off-white below. Young are silvery (fig. 38) until about 

the age of 8 weeks when numerous irregular blotches 

of grayish black appear on the body (Jennings, 1988). 

Meristics for Bighead Carp are given in appendix B.

The Bighead Carp is sexually dimorphic. Males 

possess a bony, sharp edge along the dorsal surface 

of several of the anterior pectoral rays. This feature is 

absent in females. Chang (1966) suggested that this 

secondary sex characteristic is formed long before the 

males reach maturity, and lasts throughout life.

Similar Species

The presence of a ventral keel differentiates the 

Bighead and Silver Carps from all native cyprinids 

except the Golden Shiner. Bighead and Silver Carps

have smaller and more numerous (>60) lateral-line 

scales than the Golden Shiner (39-51). Additionally, 

Bighead and Silver Carps have only four teeth in a single 

row (per side). In contrast, the Golden Shiner typically 

has five pharyngeal teeth in a single row (per side). 

The Bighead Carp can be distinguished from the 

Silver Carp, its close relative, by differences in the 

ventral keel and gill rakers. Gill rakers of Bighead Carp 

lack the fused condition that forms a sponge-like apparatus in Silver Carp. The ventral keel of the Bighead 

Carp extends forward only to the base of the pelvic fins, 

whereas the ventral keel in Silver Carp extends to the 

anterior part of the breast, almost to the junction of the 

gill membranes (fig. 36). When apressed, the pectoral 

fin of the Bighead Carp extends beyond the pelvic base; 

however, the pectoral fin does not reach the pelvic base 

in Silver Carp. Typically, the eyes of the Bighead Carp 

are slightly lower on the head than those of the Silver 

Carp; however, this characteristic may not be diagnostic. 

Additionally, adult Bighead Carp have irregular gray 

or black blotches covering the body that are absent in 

Silver Carp. 

The name “Bigheaded Carps” is often applied 

collectively to include all the Hypophthalmichthys

species.

Variation

Bighead Carp have been artificially hybridized with 

Grass Carp (see Grass Carp account). Hybridization 

has also been achieved with Common Carp (Makeyeva, 

1968, 1972) and Silver Carp (see Silver Carp account). 

Jennings (1988) reviewed the history of hybridization 

(including techniques used) and morphological characteristics of the hybrids.

Reproduction

Maturity is reached at 2-4 years in subtropical/ 

tropical locales and 5-7 years in temperate regions 

(Kuronuma, 1968; Abdusamadov, 1987). Age to maturity 

varies with food supply and environmental conditions 

(Huet, 1970; Bardach and others, 1972). Males generally mature a year earlier than females (Opuszynski 

and Shireman, 1995). Opuszynski and Shireman (1995) 

reviewed gonad condition through the stages of development. Fecundity increases with mass (Verigin and others, 

1990) and can range from about 280,000 to >1,000,000 

eggs (Vinogradov and others, 1966; reviewed in 

Opuszynski and Shireman, 1995). Larval development 

was reviewed in Jennings (1988).

Figure 37. Pharyngeal teeth (0,4-4,0) from Bighead 

Carp, SIUC 23919, 207 millimeter SL, from Washington County, Illinois.

Figure 38. Juvenile Bighead Carp. (Photo by Noel Burkhead.)

52  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
In China, where they are native, Bighead Carp 

spawned at temperatures between 26-30 °C in the 

Yangtze River (Chang, 1966, in Opuszynski and 

Shireman, 1995) and as low as 18 °C in the Han River 

(Zhou and others, 1980). Spawning habits of Bighead 

Carp in the U.S. have not been well documented; 

although a preliminary study suggested that the lower 

Missouri River is conducive to spawning, due to its 

similarity with areas used for spawning in the native 

range (for example, rising water and 22 °C temperature) 

(Schrank and others, 2001). For additional information on spawning requirements, see the section entitled 

“Spawning requirements of Chinese carps” in the Grass 

Carp account.

Ecology

The Bighead Carp is a large species that may grow 

>1 m TL and up to 40 kg in as few as 9 years (Baltagi, 

1979, in Jennings, 1988). Individuals up to about 1.3 m 

TL have been captured (Xie Ping, 2003) and maximum 

size is probably >1.5 m TL. Maximum weight is >50 kg 

(Li and Mathias, 1994). 

The Bighead Carp is one of several large Chinese 

carps introduced into the U.S. In its native range, the 

species occurs in large rivers from temperate to subtropical climates. An important aquaculture species, the 

Bighead Carp has been widely introduced throughout 

much of the world and now occurs in a variety of habitats and climates (Lever, 1996; Fuller and others, 1999; 

Xie Ping, 2003). Similar to Silver Carp, the Bighead 

Carp often swims near the water surface; however, it is 

less likely to leap out of the water when disturbed (Li 

and Mathias, 1994). The thermal maximum temperature 

(derived from laboratory studies) was 38.8 °C and the 

preferred temperature was 25.3 °C (Bettoli and others, 

1985). Liang and Wang (1993) reported the maximum 

pH for culture was 9.24. Egg hatching was delayed 

below pH 6.5 and increased mortality and deformation of larvae occurred below pH 6.0 (Li and Zhang, 

1992). However, sensitivity to low pH decreased with 

age (Li and Zhang, 1992). Median lethal concentration 

of ammonia was determined as 1.12 mg/L (Gulyás and 

Fleit, 1990). 

Oxygen consumption (per gram of body mass) 

has been shown to increase with increased water 

temperature and decrease with fish age and mass (Chen 

and Shih, 1955; Woźniewski and Opuszynski, 1988). 

Negonovskaya and Rudenko (1974) demonstrated that 

juveniles were tolerant of oxygen levels lower than 

0.5 mg/L. Laboratory studies have shown that juveniles 

can tolerate salinities up to 8 ppt for a short period 

of time (Chervinski, 1980). Salinity tolerance of fry 

increased with fish age, ranging from 2.3 ppt for 11-day 

olds to 7.6 ppt for 35-day old fish (Garcia and others, 

1999). Larvae are known to migrate to brackish-water 

areas of the Caspian Sea where salinities range from 

6-12 ppt (Abdusamadov, 1987). 

Bighead Carp larvae feed primarily on zooplankton and to a lesser extent on phytoplankton and other 

suspended material (Korniyenko, 1971; Cremer and 

Smitherman, 1980; Burke and others, 1986; Dong and 

Li, 1994; reviewed in Jennings, 1988). Adults are filterfeeders that primarily consume phytoplankton in the 

water column. Opportunistic feeding has been reported, 

with individuals seasonally shifting from zooplankton 

to phytoplankton, based on the abundance of the food 

source (Nikol’skiy and Aliyev, 1974; Burke and others, 

1986; Xie Ping, 2003). 

The Bighead Carp has been extensively transferred 

and cultured in aquaculture facilities for water-quality 

management. The species is thought to improve water 

quality of ponds by removing plankton, especially 

filamentous blue-green algae (Voropaev, 1968; Aliyev, 

1976; Cremer and Smitherman, 1980; Opuszynski and 

Shireman, 1993; Dong and Li, 1994). However, some 

researchers reported that Bighead Carp made no difference in algal density (Burke and others, 1986).

Native Distribution

The Bighead Carp is native to rivers of eastern Asia 

from southern China north into far eastern Russia (Li 

and Fang, 1990).

U.S. Introductions

The first introduction of Bighead Carp in the 

U.S. was in 1972 when a private Arkansas fish farmer 

introduced the species in an attempt to improve water 

quality in fish ponds (Fuller and others, 1999). By the 

early 1980s, the species was taken from open waters 

of the Ohio and Mississippi rivers, likely as a result of 

escapes from aquaculture facilities (Jennings, 1988). 

The Bighead Carp is now firmly established in the 

Mississippi, Ohio, and Missouri rivers, which is not 

surprising, given the similarities of these systems to 

those in the native range. Juveniles have also been taken 

in small (4 m width) streams in southern Illinois (J. 

Stewart, SIUC, personal commun. need date). 

Bighead Carp  53
Ha

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REPRODUCINGREPORTEDSTATES WITH RECORDS

EXPLANATION

Bighead Carp

Hypophthalmichthys nobilis

Alaska

Plate 7. Distribution of Bighead Carp in the United States. See Methods for details regarding data used to create maps, definitions of “reproducing” and “reported” and shading of HUCs and states.

54  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Ide

Leuciscus idus (Linnaeus 1758)

the identification of the species. Ide can be distinguished 

from most native North American cyprinids by the 

following combination of characteristics: pharyngeal 

teeth 3,5-5,3, no barbels, lateral-line scales 55-63, and 

usually 8 branched dorsal rays. Ide can be distinguished 

from other non-native cyprinids by the combination of 

a short dorsal fin (usually 8 branched dorsal rays) and 

55-63 lateral-line scales. 

Description

The Ide (fig. 39) is a medium-sized fish, typically 

growing 30-43 cm TL and weighing 680 g (Wheeler, 

1978). Maximum size is about 1 m TL and up to 8 kg 

(Berg, 1964). It has a typical minnow-shaped body 

that is moderately thick, and older adults have a raised 

“humped back” nape. Lateral-line scales number 55-63. 

The snout is blunt and the mouth is small, terminal, and 

oblique. Gill rakers are short, widely spaced, and number 

10-14 on the first arch. The pharyngeal teeth are conic, 

smooth (not serrated), and arranged in two rows (usually 

3,5-5,3; fig. 40). The dorsal fin is short, with iii (7-10) 

rays, and usually originates over the posterior part of the 

pelvic fin base. The anal fin has iii (9-13) rays. Adults 

are dark on the back and sides above the lateral line. The 

lower parts of the sides are light or silvery. The fins are 

red, especially the anal fin and paired fins. Meristics for 

Ide are given in appendix B 

Similar Species

The Ide is superficially similar to many native 

North American cyprinids and does not possess a unique 

characteristic that sets it apart from native species. Thus, 

the use of regional or state fish guides is important in 

Figure 39. Ide, UF 85165, 113 millimeter SL, from the Danube River, Austria.

Figure 40. Pharyngeal teeth (3,5-5,3) of Ide, UF 85165, 

113 millimeter SL, from the Danube River, Austria.

  55
Variation

A golden variety cultured for ornamental garden 

ponds (“Golden Orfe”) is pale yellow to orange, often 

with dark patches (Wheeler, 1969). 

Two subspecies are recognized: Leuciscus idus idus

and Leuciscus idus oxianus, Turkestan Ide (Bănărescu, 

1964; Berg, 1964). 

Ide hybridize with other European cyprinids (including Common Carp and Rudd; Schwartz, 1972, 1981). No 

hybrids with native North American fishes are known.

Reproduction

In Europe and Asia, Ide matures at 3-5 years and 

spawns in April or May (Berg, 1964; Wheeler, 1969; 

Cala, 1976). In a Swedish study, Ide matured between 

31.5 and 43.1 cm TL, with males reaching maturity at 

a size about 3 cm smaller than that of females (Cala, 

1971). In Romania, the Ide attains sexual maturity at 

lengths of 22.5-33 cm and an age of 3 years (Bănărescu, 

1964). In contrast, Ide inhabiting a reservoir in a more 

northern location (Finnish Lapland) reached maturity at 

a larger size and older age (6-7 years) (Mutenia, 1978). 

Ide spawns in weedy or sandy shallow areas where the 

adhesive eggs attach to stones or vegetation (Wheeler, 

1969; Cala, 1970). Spawning begins in the spring once 

the water reaches a temperature of about 5 °C for 2-3 

days (Cala, 1970). Wieser (1991) reported that spawning begins when water is about 7-14 °C. Fecundity 

ranged from 39,000-114,000 eggs (average 88,000) in 

the Dnieper (Berg, 1964), from 15,000-125,280 eggs in 

Romania (Bănărescu, 1964) and from 42,279-263,412 

eggs in Sweden (Cala, 1971). Fecundity increases 

linearly with fish mass (Cala, 1971). Eggs hatch in about 

5 days at 18.5-22 °C, but incubation time increases 

in cooler temperatures (Cala, 1970; Florez, 1972a). 

Optimal temperature for embryonic development is 

12-18 °C (Wieser, 1991). 

Ecology

The Ide typically grows to 30-43 cm TL and 680 g 

(Wheeler, 1978); however, individuals can reach 1 m 

TL and up to 8 kg (Berg, 1964). Typical habitat includes 

pools and slow-flowing or still waters; however, deeper 

waters are sometimes used in winter (Wheeler, 1969). 

Page and Burr (1991) reported the species from clear 

pools of medium to large rivers as well as ponds and 

lakes. Wheeler (1978) noted that the Ide inhabits 

the lower reaches of large rivers, lowland lakes, and 

brackish estuaries of rivers, adding that it schools in 

clean, deep water, moving into shallow freshwater to 

spawn in the spring. Zhadin and Gerd (1963) reported 

it was one of the most common fishes in reservoirs on 

the Ob, Novosibirsk, and Bukhtarma-Zaisan rivers of 

the former Soviet Union. Seeley (1886) reported that the 

species is not confined to freshwaters, and is found in the 

Baltic Sea. Cala’s (1970) study of the River Kävlingeån 

in Sweden reported Ide spent the first year of life in the 

river, and then joined older fish migrating to the Baltic 

Sea during the summer months. The species returned to 

the river in the autumn and remained near the mouth and 

in the lower reaches throughout the winter (Cala 1970). 

After spawning in the spring, Ide returned to coastal 

waters (Cala 1970). Specimens in the River Kävlingeån 

were found to be as old as 14 years.

Laboratory studies showed that mortality of larvae 

and juveniles was significant at oxygen concentrations 

<2 mg/L (Florez, 1972b). Cala (1970) noted that fish 

kills have been noted since 1910 in River Kävlingeån, 

Sweden, as a result of low oxygen content, high temperatures, and pollution. Upper lethal temperature of larvae 

and juveniles acclimated to 6-22 °C, varied from 24-

29 °C, and was lower in fish acclimated to lower water 

temperatures (Florez, 1972a).

Ide feeds on insect larvae and adults, cladocerans, worms, spawn of other fishes, small mollusks, 

diatoms, and filamentous algae (Zhadin and Gerd, 1963; 

Berg, 1964; Wheeler, 1969, 1978; Mutenia, 1978). 

Other dietary items include macrophytes, detritus, and 

small fishes (Zhadin and Gerd, 1963; Lammens and 

Hoogenboezem, 1991). In Sweden, small (10-80 mm 

TL) Ide ate cladocerans and copepods, but Ide >140 mm 

ate plants, isopods, oligochaetes, and insects (Cala, 

1970). 

Native Distribution

The Ide is native to most of Europe and Western 

Asia (see Berg, 1964 for details).

U.S. Introductions

The Ide was first imported to the U.S. in 1877 and 

was cultured by the U.S. Fish Commission and subsequently distributed to several state agencies and individuals (Fuller and others, 1999). Escapes from commercial 

and government ponds (especially during flooding) have 

expanded its range in the U.S. The species has been 

recorded from at least 22 states, but documentation of 

56  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
its true status in the U.S. is poor and often contradictory 

(Fuller and others, 1999). The states where the Ide is 

reported from open waters include those that received 

shipments from the U.S. Fish Commission during the 

late 1800’s. 

There have been reports of localized, reproducing 

populations in a few areas, but it is uncertain whether 

any still persist. A reproducing population was discovered in a small pond in the Connecticut River drainage 

of Connecticut in the early 1960s, but by the mid-1980s 

that population was reportedly eradicated (Whitworth, 

1996; Fuller and others, 1999). Similarly, a reproducing population of Ide in a private pond in Maine was 

eradicated. Different domesticated forms, (for example, 

“Golden Orfe”) are occasionally kept in garden ponds, 

sometimes in combination with Goldfish and Koi. 

Golden Orfe is also present in commercial aquaculture 

facilities in California (Dill and Cordone, 1997).

Ide  57
Ha

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ERADICATEDREPORTEDSTATES WITH RECORDS

EXPLANATION

Ide

Leuciscus idus

Alaska

Plate 8. Distribution of Ide in the United States. See Methods for details regarding data used to create maps, definitions of “eradicated” and “reported” and shading of HUCs and states.

58  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Black Carp

Mylopharyngodon piceus (Richardson 1846)

present, consisting of a single tooth (possibly two in 

rare instances) on one or both sides. Dentition formula 

is typically 0,4-5,0 or 1,4-4,1. Juvenile and adult Black 

Carp (31-330 mm TL) pass through several generations 

of pharyngeal teeth (Liu and others, 1990). In small 

Black Carp (<30 mm TL), the pharyngeal teeth may be 

conical. 

During the reproductive season, male Black Carp 

develop breeding or nuptial tubercles, although these 

may not always be observable (Bardach and others, 

1972). Breeding tubercles have been reported on the 

interorbital region, pectoral-fin rays, operculum, and 

sides of the body (Kimura and Tao, 1937; Wu and others, 

1964b; Chang, 1966; Zhong and others, 1980). Tubercles 

are absent in females (Chang, 1966). 

Similar Species

Few native North American fishes can be confused 

with Black Carp. Its large adult size distinguishes Black 

Carp from most native minnows, although a few large 

catostomids (suckers) and cyprinids have a body shape 

superficially resembling Black Carp. Several native 

fishes have heavy pharyngeal teeth modified for feeding 

Description

The Black Carp (fig. 41) is a large cyprinid, often 

exceeding 1 m SL. The reported maximum size is about 

2 m TL and 70 kg (Nico and others, 2005). The body 

is somewhat stout, rather elongate, and cylindrical to 

slightly compressed with a short and relatively deep 

caudal peduncle. The scales are relatively large, ranging 

from 39-46 along the lateral line. The head is relatively 

short, with eyes of moderate size. The snout is slightly 

rounded. The mouth is relatively small to moderate in 

size, placed terminally or slightly subterminally, and 

lacking barbels. Gill rakers are short and stout, usually 

numbering 18-21 (range 14-23). The short dorsal fin 

has iii (7-9) rays. The anal has iii (7-9) rays. The dorsalfin origin is slightly anterior to pelvic-fin origin. The 

caudal fin is large and forked. Body coloration is somewhat variable. Typically, individuals are dark brown or 

blue-gray to black and the fins, in particular, are darkly 

pigmented (fig. 42). Meristics for Black Carp are given 

in appendix B (also see Nico and others, 2005).

The pharyngeal teeth generally form a single 

row of four or five large molariform teeth per side 

(fig. 43). Occasionally an outer (secondary) row is 

Figure 41. Black Carp, SIUC 46739, 390 millimeter SL, from Randolph County, Missouri.

  59
on mollusks, similar to Black Carp. Nevertheless, in all 

cases the combination of size, number, shape, and placement of the pharyngeal teeth of native species is different from that found in Black Carp. 

The Black Carp is most similar to its close relative, 

the Grass Carp, particularly in terms of body size and 

shape, and the position and size of fins and eyes (Nico 

and others, 2005). Anatomy of the pharyngeal teeth 

is the main characteristic used to distinguish the two 

species, although body color differences may also be 

useful. Pharyngeal teeth of Black Carp (about >30 mm 

TL) are large, molariform, and relatively smooth (without grooves or hooks of any kind; fig. 43), whereas those 

of Grass Carp are elongate with grooves or serrations. 

Small Black Carp (about <30 mm TL) have pharyngeal 

teeth that are somewhat conical and could be confused 

with the teeth of Grass Carp. 

The body and fins of Grass Carp are generally 

lighter in color than those of Black Carp; however, color 

may vary with age, habitat, and season (Nico and others, 

2005). Whereas the Black Carp is rather darkly colored, 

the Grass Carp is olivaceous, silvery white, or olivebrown above and silvery below, with most fins only 

partially pigmented (sometimes described as dusky). In 

both species, the body is counter-shaded, lighter below 

than above. In some Black Carp, the ventral part of the 

body may appear almost white, particularly beneath the 

head region. Although little information exists on color 

differences between juvenile Black Carp and Grass Carp, 

color pattern is probably less reliable in distinguishing 

between small juveniles of the two species, because of 

habitat influence. For example, Grass Carp inhabiting 

tannic waters (sometimes referred to as “black water”) 

typical of the southern U.S. can be darkly pigmented and 

confused with Black Carp. 

Descriptions of Black Carp in the literature and 

our own examination of live and preserved specimens 

indicate that a few other traits may be useful in distinguishing Black Carp from Grass Carp. However, not 

all of these differences have been adequately confirmed 

(Nico and others, 2005). Moreover, these additional 

traits may exhibit more variation than pharyngeal teeth 

and, therefore, are appropriately used only in combination with teeth anatomy and body color. These additional 

traits include: number and relative size of gill rakers, 

shape of head and snout (for example, interorbital width 

and head length), relative length of the intestine, and 

color of the peritoneum. Howells (1992) reported that 

differences in gill-raker counts distinguish Black Carp 

from Grass Carp. However, our review of the literature 

and counts on specimens indicate there is overlap, with 

Black Carp having 14-23 (usually 18-21) gill rakers, 

and Grass Carp typically having 12-16. Gill rakers in 

both species are relatively small, but an examination of 

30 Black Carp and 30 Grass Carp revealed that those 

of Black Carp were slightly shorter and stouter. Slight 

differences in the shape and slope of the head have been 

observed. For example, our measurements of preserved 

specimens (about 80-100 mm SL) indicate that the ratio 

of the interorbital width (IOW) divided into head length 

Figure 42. Black Carp (261 millimeter SL) from the species’ native range 

in the Chang (Yangtze) River Basin, Hunan Province, People’s Republic of 

China. (Collected by C. Zhang, F. Fang, and colleagues during trip financed 

by the European Commission, INCO-DEV program, project ECOCARP, 

contract number ICA4-CT-2001-10024. Photograph courtesy of Fang Fang 

Kullander, Swedish Museum of Natural History, Stockholm.)

Figure 43. Pharyngeal teeth of Black Carp, SIUC 

46739, 390 millimeter SL, from Randolph County, 

Missouri. (Also see fig. 9, p. 13.)

60 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
(HL), may be a useful distinguishing characteristic. 

Measurements ranged from 35-45 percent in Black Carp 

versus 48-56 percent in Grass Carp. Black Carp have a 

relatively short digestive tract (intestinal length is about 

1-2 times TL), whereas Grass Carp have a longer, more 

coiled digestive tract (intestinal length about 2.5 times 

TL; Nico and others, 2005). Based on our own observations and information in the literature, the peritoneum of 

juvenile and adult Black Carp is dark, whereas in Grass 

Carp the membrane is generally silver, although heavily 

mottled with black (fig. 10 in Key). 

Variation

There are no recognized subspecies for Black Carp. 

However, Bíró (1999) suggested that differences in 

pharyngeal teeth counts provide possible evidence for 

two subspecies in China.

Hybrids in nature have not been reported. However, 

the Black Carp has been artificially crossed (with limited 

success) with Grass Carp, Silver Carp, Bighead Carp, 

Common Carp, and Black Bream (Megalobrama terminalis; Ryabov, 1979; Evtushenko and others, 1994; Bíró, 

1999; Nico and others, 2005). 

Reproduction

The reproductive requirements of Black Carp are 

similar to those of Grass Carp (Nico and others, 2005). 

Please refer to section entitled “Spawning requirements 

of Chinese carps” in the Grass Carp account.

Ecology

The Black Carp is a large cyprinid, often exceeding 1 m SL and with a maximum size of about 2 m TL 

and 70 kg (Nico and others, 2005). The typical habitat 

includes reaches of large rivers that are below 200 m 

above sea level (Li and Fang, 1990), such as channels 

of lowland rivers and associated floodplain lakes and 

backwaters. The species also occurs in artificial habitats 

(including canals), and some populations survive in 

lakes and reservoirs, although reproduction and completion of their life cycle require a connection to flowing 

waters (Nico and others, 2005).

Nico and others (2005) reviewed information 

on the environmental tolerances of Black Carp. The 

species is tolerant of temperatures from about 0.5-

40 °C. Reproduction and egg development generally 

occur between 18-30 °C. The Black Carp is known to 

occasionally inhabit the deltas of rivers (for example, 

Yangtze River, China), where it may encounter brackish 

waters. However, information on salinity tolerance of 

Black Carp has not been reported. 

The species is tolerant of pH from 6-10 for limited 

periods of time; however, the preferred range is from 7 

or 7.5-8.5. Black Carp is tolerant of oxygen levels as low 

as 2 mg/L. 

The diet of Black Carp was reviewed by Nico and 

others (2005). Larvae and small juveniles feed almost 

entirely on small invertebrates (such as zooplankton and 

aquatic insects). Larger juveniles and adults are bottomfeeders that predominantly prey on snails and bivalve 

mollusks, although crayfish and other benthic invertebrates are sometimes consumed. The heavy pharyngeal 

arches and large molariform teeth of Black Carp are 

adapted to crush mollusk shells (Liu and others, 1990; 

Nico and others, 2005). 

Native Distribution

The native range of Black Carp includes most major 

Pacific Ocean drainages of eastern Asia from the Amur 

River Basin south to the West-Pearl River Basin, and 

possibly the Red River of northern Vietnam (Nico and 

others, 2005).

U.S. Introductions

Black Carp was first imported into the U.S. in the 

1970s, and by the 1990s the species was being used 

in fish farms in several southern states to control pond 

snails (Nico and others, 2005). Thirty Black Carp were 

reported as having escaped into the Osage River from a 

Missouri fish farm during a major flood in April 1994. 

Because of its widespread use to control snails, escapes 

from aquaculture ponds have probably added to the 

wild population. During recent years there have been 

reports of Black Carp being captured in the wild. The 

first published report was that of a single Black Carp 

taken by a commercial fisher from Horseshoe Lake 

in southern Illinois in March 2003 (Chick and others, 

2003). Nico and others (2005) investigated other reports 

and found evidence that wild populations of Black Carp 

may have been present in the lower Mississippi River 

Basin, largely in and around the Red River of Louisiana, 

since the early 1990s. Reproduction in the Mississippi 

River has not been documented, but new information 

and recent collections suggest the species is likely 

established in the lower part of the Mississippi Basin and 

possibly elsewhere in the basin (Nico and others, 2005). 

Black Carp  61
Ha

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Black Car

p

Mylopharyngodon piceus

REPORTEDSTATES WITH RECORDS

EXPLANATION

Alaska

Plate 9. Distribution of Black Carp in the United States. See Methods for details regarding data used to create maps, definition of “reported” and shading of HUCs and states.

62  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Bitterling

Rhodeus sericeus (Pallas 1776)

Breeding males are brilliantly colored (Smith and 

others, 2004). They turn iridescent along the sides and 

the stripe along the mid-line of the body turns bright 

blue (Smith, 1985). In addition, the dorsal and anal 

fins, breast, and belly become orange to blood-red. 

According to Smith and others (2004), the dorsal fin of 

mature males is almost black, with a red triangle at its 

Description

The Bitterling (fig. 44) is a small species, rarely 

exceeding 7 cm SL (Smith and others, 2004). Maximum 

size is about 11 cm TL (Page and Burr, 1991). The 

species is deep-bodied and moderately compressed, with 

the back arched anterior to the dorsal fin. The scales 

are moderately large, with 32-45 lateral scale rows. 

The lateral line is absent or incomplete, with only 0-10 

pored scales. The head is relatively small and the mouth 

is small, oblique, and lacks barbels. The upper jaw is 

slightly longer than the lower one. The pharyngeal teeth 

are hooked and in a single row (0,5-5,0; fig. 45). Gill 

rakers on the first arch range from 9-16. The dorsal fin 

has with ii-iii (7-11) rays and originates slightly anterior 

to the anal fin. The anal fin has ii-iv (6-11) rays. The 

caudal fin is moderately forked, with roughly equally 

sized lobes. The back is gray-green to gray-brown, and 

the sides and belly are silvery. The sides may include 

some pink. The fins are pale orange, except in breeding 

males when the dorsal and anal fins become bright red. A 

gray-green metallic stripe runs along the mid-line of the 

body from just under the dorsal fin to the caudal peduncle. Meristics for Bitterling are given in appendix B.

Figure 44. Bitterling, TU 8889, 71.2 millimeter SL, from Westchester County, N.Y.

Figure 45. Pharyngeal teeth of Bitterling, TU 8889, 

71.2 millimeter SL, from Westchester County, N.Y.

  63
tip, and the anal fin is red with a dark border. They also 

noted that the upper part of the iris is red in sexually 

mature males and remains pigmented the remainder of 

life. During the spawning season, mature males also 

develop two patches of white nuptial tubercles on either 

side of the head (Wheeler, 1978; illustrated in Schmidt 

and McGurk, 1982). The color of females remains 

unchanged during the breeding season: gray-green 

dorsally, silver laterally, and yellow ventrally, and without red pigment around the iris (Smith and others, 2004). 

Breeding females develop a long, tube-shaped ovipositor anterior to the anal fin. The ovipositor is extended 

during spawning, but is retracted into the body at other 

times (Smith and others, 2004). Length of the ovipositor 

is variable; it is longest shortly before or after spawning when the structure may exceed the body length of 

the female (Seeley 1886; Berg 1964; Smith and others, 

2004). Outside the spawning season females retain an 

ovipositor. Although much reduced in size, the organ 

remains obvious and readily distinguishes females from 

males (Smith and others, 2004). 

Similar Species

The Bitterling can be distinguished from most 

native North American cyprinids as well as all other 

non-native cyprinids by a combination of characteristics, 

including large scales (32-45 lateral scale rows), a deep 

body, and short lateral line (0-10 pored scales). 

Variation

The taxonomy of Bitterling remains problematic 

(Smith and others, 2004). Bănărescu (1964) recognized 

three subspecies: Rhodeus sericeus amarus ranges 

from the Seine River of France east through central and 

eastern Europe to the Ural Mountains (but not Spain, 

Italy, England, or Scandinavia); Rhodeus sericeus sericeus from the Amur River Basin region; and Rhodeus 

sericeus sinensis from the Yangtze River Basin. Some 

researchers consider the western populations a separate 

species, R. amarus (Smith and others, 2004). However, 

Holčík and Jedlička (1994) documented clinal gradation 

in characteristics used to separate the geographically 

isolated subspecies and recommended ending the use of 

subspecies designations. They noted that characteristics 

used to separate the eastern and western forms were size 

and temperature dependent.

Only a few hybrids are reported for the Bitterling, 

and all are from crosses with Asian cyprinids (Schwartz, 

1972, 1981).

Reproduction

Sexual maturity is reached in the second to fourth 

year (Nikolsky, 1954; Zhul’kov and Nikiforov, 1988). 

In Europe and nearby regions, spawning occurs between 

April and August, typically with a peak in May (Smith 

and others, 2004). According to Reichard and others 

(2004), spawning is determined by photoperiod and 

water temperature. Seeley (1886) noted that spawning occurred from May to August in the Seine River 

(France), and during April in Austria. Wheeler (1969) 

reported spawning in April and June in northwestern 

Europe. Zhul’kov and Nikiforov (1988) reported spawning at temperatures from 12-24 °C in Russia. 

Reproduction of Bitterling is unusual, involving a symbiotic relationship with various species of 

freshwater mussels from the families Unionidae and 

Margaritiferidae (Smith and others, 2004). During the 

spawning season, the brightly colored males defend 

territories around mussels. Gravid females use their 

elongate ovipositor to deposit their eggs into the mantle 

cavity of the mussel. Male Bitterling then fertilize the 

eggs inside the mussel by shedding their sperm over the 

inhalant aperture of the mussel so that water entering the 

mussel carries the sperm to the eggs (Smith, 1985; Smith 

and others, 2004). Sterba (1973) reported that females 

condition the mussels to the stimulus by repeatedly 

nudging them with their mouth, thus ensuring against 

closing of the valves during the insertion of the ovipositor. The same female may use a number of mussels, and 

she deposits only one or two yellow, oval eggs into each 

(Seeley 1886; Axlerod and Schultz, 1955). The ovipositor is only present during the spawning season, after 

which it gradually shortens until reduced to a papilla 

(Seeley 1886; Sterba, 1973). Smith (1985) reported that 

the ovipositor of one female shrank to one-third of its 

maximum length within 3 days after spawning. Breder 

(1933) demonstrated that the Bitterling could use freshwater mussels native to the U.S. for reproduction (for 

example, Elliptio complanata and Pyganodon [formerly 

Anadonta] cataracta). Contrary to what was previously 

thought, there is evidence indicating the Bitterling 

is selective about which mussel species are used for 

spawning (Smith and others, 2004).

Fecundity of the Bitterling is low compared to 

cyprinids that broadcast their eggs. A fecundity of only 

31-53 eggs per female was reported in the population 

inhabiting the Bronx River, New York (Schmidt and 

McGurk, 1982). Zhul’kov and Nikiforov (1988) reported 

a fecundity of 203-408 eggs per female in a Russian 

64  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
river. Aldridge (1999) studied an introduced population 

of Bitterling in Britain, and documented the large size of 

the eggs (2.6 X 1.7 mm). The elliptical shape of the eggs 

(versus the more common spherical shape) is reportedly an adaptation to increase transport of respiratory 

and excretory products across the membrane (Aldridge, 

1999). It has been hypothesized that female Bitterling 

discriminate among egg hosts by inspecting flow velocity and oxygen content of water emerging from the 

exhalant siphon of the mussels (Smith and others, 2001; 

Mills and Reynolds, 2002). The stages of development 

from the egg to the free-swimming larvae are described 

and illustrated in Aldridge (1999).

The larvae stay inside the mussel for 3-4 weeks, 

until the egg sac is absorbed and they have reached a 

length of about 11 mm (Aldridge, 1999). Larval drift 

of Bitterling in the Danube Basin peaks in late June 

(Jurajda, 1998; Reichard and others, 2002). Jurajda 

(1998) reported that the larvae drifted at night near the 

surface of the water. The larval period of the precocial 

Bitterling is shorter in duration than many other cyprinids (Reichard and Jurajda, 1999). Phosphorus pollution 

(500 μg/L and higher) has been shown to increase the 

rate of premature expulsion of larvae from the mussels, 

leading to increases in larval mortality (Reynolds and 

Guillaume, 1998). 

Ecology

The Bitterling is a relatively short-lived species, 

generally surviving only about 5 years (Nikolsky, 1954). 

Maximum size is 11cm TL (Page and Burr, 1991), but it 

usually only grows to 6-7 cm in Europe (Wheeler, 1969). 

A total of 138 individuals ranging from 38-66 mm SL 

(mode = 48 mm SL) were taken from the Bronx River, 

New York, by Schmidt and McGurk (1982).

The Bitterling inhabits slow-flowing or still waters, 

such as ponds, lakes, marshes, muddy and sandy pools, 

and river backwaters (Wheeler, 1969; Page and Burr, 

1991). Because the Bitterling depends on freshwater 

mussels to reproduce, its range is restricted (Smith and 

others, 2004). Przybylski and Zieba (2000) reported that 

in Poland the preferred habitats were characterized by 

low flow and covered by vascular plants.

The species is omnivorous, feeding on both invertebrates (especially in the juvenile stage) and plant 

matter. Seeley (1886) reported diatoms and algal fragments from the long, coiled intestines of the Bitterling. 

Wheeler (1969) reported that European Bitterling fed 

on phytoplankton, crustaceans, insect larvae, tubificid 

worms, and vegetable detritus. Five specimens examined 

by Schmidt and McGurk (1982) from the Bronx River, 

New York, contained diatoms and detritus. Przybylski 

(1996) documented that the diet of small (22-36 mm) 

individuals primarily consisted of chironomids, whereas 

larger fish (50-75 mm) fed on detritus and plant matter. 

Feeding occurred primarily during the day (Przybylski, 

1996). Koutrakis and others (2003) documented that the 

diet of a population of Bitterling in Greece consisted of 

algae, insects, crustaceans, and organic and inorganic 

matter.

The Bitterling derives its name from its apparently 

noxious taste (to both humans and fishes), and thus 

was not recommended as a bait fish by Seeley (1886). 

Wheeler (1969) suggested its main appeal was as an 

aquarium fish, and hypothesized that populations found 

in Britain were due to aquarium releases.

Native Distribution

The Bitterling has a disjunct distribution that has 

lead to some taxonomic confusion. The species occurs 

in Central and Eastern Europe from the Seine River of 

France to the Ural Mountains (but not in Spain, Italy, 

England, or Scandinavia). Pallas described the species in 

that region as Rhodeus sericeus. Bitterling also naturally 

occurs in the Amur River Basin of eastern Asia, where 

it was described as Rhodeus amarus by Bloch (now 

Rhodeus sericeus amarus). Additionally, a subspecies of 

Bitterling is found in the Yangtze River Basin (Rhodeus 

sericeus sinensis). There is a wide geographical gap in 

the northern part of Asia separating the ranges of the 

European subspecies from those of eastern Asia.

U.S. Introductions

The only known introductions of Bitterling into the 

U.S. were in the state of New York. The species was 

introduced into the Sawmill and Bronx rivers sometime 

before 1925 (Dence, 1925; Myers, 1925). No Bitterling 

have been collected in the Sawmill River since 1951, 

and that population is assumed to be extirpated (Schmidt 

and others, 1981). In the early 1980s, the Bronx River 

population was estimated to number only about 900 

individuals and inhabit 1-2 km of the river (Schmidt and 

McGurk, 1982). Although native mussels (needed for 

reproduction) still occur in the Bronx River, the population of Bitterling appears to be declining (R. Schmidt, 

personal commun., 2005; J. Rachlin, personal commun., 

2005).

Bitterling  65
Ha

waii

REPRODUCINGSTATE WITH RECORDS

EXPLANATION

Bitterling

Rhodeus sericeus

Alaska

Plate 10. Distribution of Bitterling in the United States. See Methods for details regarding data used to create maps, definition of “reproducing” and shading of HUCs and states.

66  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Rudd

Scardinius erythrophthalmus (Linnaeus 1758)

Coloration of non-nuptial adult Rudd is silvery with 

a yellow-lime sheen on the upper sides grading to brassy 

on the back (fig. 48). Pigmentation on the back varies 

depending on the color of the habitat substrate. Fish from 

Description

The Rudd (fig. 46) is a medium-sized fish typically 

attaining about 30 cm TL and 0.8 kg, with a maximum 

size of about 45 cm TL and 2 kg (Berg, 1964; Wheeler, 

1969, 1978; Muus, 1971). The body is deep and moderately compressed with an arched back and a scaled 

keel between the pelvic fins and anus. The lateral line 

is complete with 37-43 scales and distinctly curved 

downward anteriorly. The snout is blunt and the mouth 

is large, terminal, and oblique. The eyes are laterally 

positioned. The cranium profile is convex to straight, 

becoming slightly concave in some larger specimens. 

Gill rakers on the outer arch range in number 10-13. 

Pharyngeal teeth are strongly serrated and borne on 

a stout arch. The dental formula is typically 3,5-5,3 

(fig. 47). The peritoneum is silvery and the intestine is 

S-shaped. The dorsal-fin origin is markedly posterior to 

the pelvic-fin insertion. The dorsal fin is slightly falcate 

and has i-iii (8-10) rays. The anal fin is moderately 

falcate and has i-iii (9-13) rays. The caudal fin is moderately forked, with the lower lobe slightly longer than the 

upper. Meristics for Rudd are given in appendix B. 

Figure 46. Rudd, SIUC 51749, 105 millimeter SL, from cultured stock in Gainesville, Florida. (The original brood 

stock came from Arkansas.)

Figure 47. Pharyngeal teeth (3,5-5,3) of Rudd, SIUC 

51749, from cultured stock, Gainesville, Florida. (The 

original brood stock came from Arkansas.)

  67
pale substrates often lack the distinctive broad middorsal 

stripe and have a dorsum that is silvery, brassy, or with a 

lime sheen. The dorsal surface of the head is straw-olive 

in color. The cheeks and opercles are silver. According to 

Wheeler (1978), all the fins are reddish and the ventral 

fins are brilliant blood red. Other authors have described 

the median fins as having a rose-orange wash and the 

paired fins as rose-orange (especially in the leading 

rays). The iris of the eye is golden with a red fleck above 

(Wheeler, 1978). The Rudd also has a golden color 

morph that is sometimes used as an ornamental pond fish 

(Maitland, 1977).

In nuptial males, the venter is silver and the sides 

are brassy progressing to bright translucent orange 

along the midback. The back and upper sides are oliveblack anterior and posterior to the dorsal fin. The dorsal 

surface of head is translucent orange. Cheeks and 

opercles are brassy-orange. The lips are orange and the 

iris is orange dorsally. The distal two-thirds of the dorsal 

fin is bright red, and the basal third is paler with oliveblack along the rays. The anal and caudal fins are bright 

red with distinct pale margins. Paired fins are red except 

the posterior 3-5 rays, which are pale. The coloration of 

mature females is similar to males, but more subdued.

Nuptial males develop fine tubercles on the head 

and body (Berg, 1964; Wheeler, 1969). Two small (76 

and 81 mm SL) sexually mature males reared in the 

laboratory exhibited fine, densely spaced tubercles on 

the head, anterior part of the body, and rays of pectoral, 

dorsal, and anal fins. Tubercles have not been reported 

in females. In both sexes, the urogenital opening is 

present just posterior to the anus and is located in a 

fleshy pit. The female urogenital opening is about twice 

the size of the male opening and is ringed with fleshy 

protuberances.

Similar Species

The Rudd is distinguished from native North 

American cyprinids by two characteristics. The Rudd has 

a scaled midventral keel (fig. 49) and a 3,5-5,3 pharyngeal tooth formula (fig. 47). The blood-red color of the 

pelvic and anal fins in specimens about >40 mm SL may 

have diagnostic utility. 

Figure 48. Adult Rudd, 104 millimeter SL, from cultured stock in Gainesville, Florida. 

(The original brood stock came from Arkansas; photo by Noel Burkhead.) 

Figure 49. Ventrolateral and posterior aspect 

of abdomen showing (A) a scaled keel in Rudd, 

(B) a partially scaled keel in hybrid Rudd X 

Golden Shiner, and (C) a naked keel in Golden 

Shiner. (From Burkhead and Williams 1991.)

(Also see to fig. 8, p. 12.)

(A)

(B)

(C)

68  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
The Rudd is most similar in appearance to the 

Golden Shiner, the only native North American cyprinid having a midventral keel. However, the keel of 

the Golden Shiner is scaleless, whereas the keel of the 

Rudd is crossed with scales. In Rudd X Golden Shiner 

hybrids the keel is partially scaled (fig 49; Burkhead and 

Williams, 1991). In both species the fins may be brightly 

colored; however, the fins of adult Golden Shiners are 

typically orange or reddish-orange, whereas those of 

Rudd are generally blood red. If there is any question 

of identity, the pharyngeal arches should be examined. 

The pharyngeal teeth of Rudd are in two rows (3,5-5,3); 

those of the Golden Shiner are in a single row (0,5-5,0).

Early development of the Rudd has been described 

by Bracken and Kennedy (1967), Kennedy and 

Fitzmaurice (1974), Cadwallader (1977), and Černý 

(1977). Newly hatched larvae possess adhesive organs 

on the head and anterior trunk. Adhesive organs have 

not been observed in the Golden Shiner (Lippson and 

Moran, 1974; Snyder and others, 1977). 

Variation

A golden color variety is sometimes used as an 

ornamental pond fish (Maitland, 1977).

A number of subspecies have been recognized 

(Bănărescu, 1964). Some are no longer considered valid; 

and a few have been elevated to distinct species (for 

example, Scardinius graecus and Scardinius scardafa;

Bogutskaya, 1997; Bianco, 2004). 

The Rudd has been reported to hybridize with a 

number of Old World cyprinids, including Goldfish, 

Common Carp, and Tench (Schwartz, 1972, 1981). 

There is one report of Rudd X Northern Pike (Esox 

lucius) hybridization (Romashov and Golovinskaia, 

1960, in Schwartz, 1972, 1981). The Rudd has also been 

artificially hybridized with Golden Shiner (Burkhead 

and Williams, 1991).

Reproduction

Age at maturity varies with geographic latitude. 

Males may be sexually mature from 1-4 years and 

females from 2-5 years. Spawning occurs in late spring 

and summer when water temperatures are above 16 °C 

(Nikolsky, 1963). Holčík (1967) suggested that the Rudd 

may be a “portional” spawner, producing two batches of 

eggs in a spawning season; the first batch being larger 

than the second. Berg (1964) reported 96,000-232,000 

eggs per female, but did not indicate the size range of 

the fish examined. Kennedy and Fitzmaurice (1974) 

reported a range of 108,000-211,000 eggs per kg of 

body mass.

In preparation for spawning, mature males appear 

at the breeding sites first. Females are present 6-8 days 

later, although actual spawning reportedly does not 

occur for another 2-3 weeks (Holčík, 1967). Pre-spawning behavior in the shallow waters of a lake in Sweden 

was described by Svärdson (1949). Large numbers of 

fish were involved in the spawning activities, with local 

aggregations near dense submerged vegetation. The 

adhesive eggs are shed on vegetation, usually along the 

shoreline (Wheeler, 1969; Cadwallader, 1977). Černý 

(1977) reported spawning on rocky substrata close to 

the banks of a reservoir. The Rudd is also known to join 

in the spawning shoals of other cyprinids (Cadwallader, 

1977; Černý, 1977; Muus, 1971).

Rudd eggs are demersal and adhesive, and 

newly fertilized eggs are translucent pale yellow to 

opaque gray-green (Cadwallader, 1977; Černý, 1977). 

Developmental rates vary widely with temperature. For 

example, Kennedy and Fitzmaurice (1974) observed that 

incubation time ranged from 4-5 days at 17.5-21.5 °C 

to 19-20 days at 10.5-11.5 °C. Larvae are about 4.5-

5.9 mm TL at hatching. Early development has been 

described by Bracken and Kennedy (1967), Kennedy 

and Fitzmaurice (1974), Cadwallader (1977), and Černý 

(1977). 

Ecology

Berg (1964) stated that adult fish are typically 

200-250 mm SL and weigh 100-300 g. However, Rudd 

from near Moscow may attain 360 mm SL and weigh 

1.5-2.0 kg (Berg, 1964). According to Muus (1971), 

the maximum size is 450 mm and 1.7 kg; however, 

Wheeler (1969) reported the British angling record as 

2.06 kg. The Rudd has a moderately long life span, and 

individuals >10 years of age are common. Kennedy 

and Fitzmaurice (1974) reported Rudd from Ireland 

as large as 1.4 kg and as old as 17 years. Coad (2005) 

commented that the Rudd life span is up to 30 years. 

The Rudd occurs in a variety of freshwater habitats, 

including subalpine oligotrophic lakes, lowland lakes, 

reservoirs, ponds, large rivers, oxbows, small streams, 

thermal springs, and in some areas, it enters brackish water (Wheeler, 1969; Kennedy and Fitzmaurice, 

1974; Aneer and Nellbring, 1976; Rheinberger and 

others, 1987). The species occupies sites that range in 

elevation from sea level to 1,829 m (Schindler, 1957). 

The Rudd’s tolerance of a variety of habitats has likely 

contributed to its wide distribution. In streams and 

rivers, it usually occurs in long, slow pools and backwaters. In ponds, lakes and reservoirs, it is usually found 

Rudd  69
in the littoral zone. The species is commonly associated vegetation that serves both as cover and a principal component of the diet (Wheeler, 1969; Kennedy 

and Fitzmaurice, 1974). The Rudd is able to tolerate 

low levels of salinity and is known to naturally enter 

brackish water. In Ireland, Kennedy and Fitzmaurice 

(1974) reported that Rudd occurred in tidal ponds of the 

Shannon Estuary and in Courtown Harbor where salinity ranges from 1-10 ppt. Individuals have also been 

captured in the northern Baltic Sea at a salinity of 7 ppt 

(Aneer and Nellbring, 1976). Experimental studies have 

shown an ability to tolerate salinity concentrations up to 

17 ppt as well as heavy chloride pollution (Hynes, 1970).

The Rudd has a diverse diet. Kennedy and 

Fitzmaurice (1974) noted that larval Rudd held in 

laboratory conditions first began to feed at 6.0-6.5 mm 

TL. At this size, they consumed unicellular algae and 

some phytoplankton. At approximately 10 mm TL the 

fish shifted their diet to cladocerans and copepods. 

Other items in the diet included larvae and pupae of 

chironomids, flies, and springtails, as well as a variety 

of small terrestrial insects. Adult Rudd (2+ years) are 

omnivorous, feeding mainly on aquatic vegetation as 

well as surface and aerial insects, snails, crustaceans, 

diatoms, and occasionally fish eggs (Hartley, 1947; 

Muus, 1971; Coates and Turner, 1977; Smith, 1985). 

Wheeler (1969) reported that Rudd in Europe consumed 

crustaceans (including copepods, ostracods, and amphipods) and occasionally small fishes.

Native Distribution

The Rudd is widespread in Europe and middle Asia 

(Bănărescu, 1964; Berg, 1964). 

U.S. Introductions

To date, the Rudd has been reported from at least 22 

states, but it may exist in additional states. Because of 

incomplete data and contradictory information, the exact 

distribution of Rudd in the U.S. and the status of many 

introduced populations remain uncertain (Fuller and 

others, 1999). 

70 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Alaska

Hawaii

REPRODUCINGREPORTEDSTATES WITH RECORDS

EXPLANATION

Rudd

Scardinius erythrophthalmus

Plate 11. Distribution of Rudd in the United States. See Methods for details regarding data used to create maps, definitions of “reproducing” and “reported” and shading of HUCs and states.

Rudd  71
Englishmen angling for Tench and other coarse fish in Bridget Lough, Ireland, 2004. (Photo by Leo G. Nico.)

72  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Tench

Tinca tinca (Linnaeus 1758)

The body is dark green on the back and greenishbrown to dark brown on the sides (fig. 52). The belly 

typically has a yellowish tinge. Body coloration may 

vary with habitat, ranging from almost black in shallow, 

muddy lakes to much lighter in running water or clear 

water lakes (Berg, 1964). The fins are dark gray to dark 

brown to black. Eyes are orange-red. An ornamental 

variety (“Golden Tench”) is orange-yellow or reddish. 

Sexual dimorphism is evident but not pronounced. 

In mature males, the second unbranched ray of the pelvic 

fins is thickened and is accompanied by a muscular 

Description

The Tench (fig. 50) is a medium-sized fish, typically 

attaining 60-80 cm TL and weighing 2-3 kg (Moyle, 

2002) with a maximum size of about 84 cm and 8 kg 

(Berg, 1964; Wheeler, 1978). The body is thick, and the 

caudal peduncle is deep and short. The skin is covered 

with a thick layer of mucous and is extremely slimy. 

Scales are small, elongated horizontally, and deeply 

embedded in the skin, leaving only 1/4-1/3 of the scale 

exposed (Berg, 1964). Lateral-line scales number 70-

120. The head is triangular, generally averaging just 

<30 percent of SL. The snout is relatively long and the 

interorbital distance is broad. The mouth is terminal, 

oblique, and small, with a single barbel at the end of 

each maxilla (corner of jaw). Pharyngeal teeth are in 

a single row, typically with either four or five on each 

side (usually 0,5-5,0 or 0,4-5,0; fig. 51). In juveniles, 

the pharyngeal teeth may be wedge-shaped and slightly 

hooked at the tip. There are about 10-16 gill rakers on 

the first arch, although anterior rakers may be difficult 

to distinguish from “throat tubercles” (Coad, 2005). The 

rakers are moderately long. The dorsal fin is rounded 

and has ii-iv (6-9) rays. The anal fin is also rounded and 

has iii-iv (5-9) rays. The caudal fin is somewhat truncate 

(squared). Meristics for Tench are given in appendix B.

Figure 50. Tench, AUM 15556, 194 millimeter SL, from Bonner County, Idaho.

Figure 51. Pharyngeal teeth (0,5-4,0) of Tench, AUM 

15556, 194 millimeter SL, from Bonner County, Idaho.

  73
protuberance from the flank. Additionally, these fin rays 

are longer, reaching past the vent and extending to the 

anal fin (Berg, 1964; Wheeler, 1978; Coad, 2005). 

Similar Species

Tench can be distinguished from native cyprinids 

by the combination of a single barbel at the end of each 

maxilla and the presence of deeply embedded, fine 

scales (generally >100 in lateral line). The dorsal fin 

is short and lacks a heavy spine-like ray, which distinguishes it from Common Carp, Goldfish, and Crucian 

Carp. Additionally, the Tench has only one pair of 

barbels (as opposed to the Common Carp, which has two 

pair), more lateral-line scales (100 or more in Tench, 40 

or fewer in Common Carp) and a squared caudal fin (as 

opposed to a forked one in Common Carp).

Variation

An ornamental variety popular in water gardens 

(called the “Golden Tench”) is orange-yellow or reddish. 

Tench have been crossed with a number of Old 

World cyprinids, including Goldfish, Common Carp, Ide, 

Bighead Carp, and Rudd (Victorovsky, 1966; Schwartz, 

1972, 1981). There are no known hybrids with native 

North American cyprinids.

Reproduction

Males generally mature in their third year, a year 

before females (Moroz, 1968; Wheeler, 1969; Moyle, 

2002; Yilmaz, 2002). Spawning is initiated when water 

temperatures reach 18 °C (Moroz, 1968; Wheeler, 1969; 

O’Maoileidigh and Bracken, 1989; Neophitou, 1993; 

Moyle, 2002). The species aggregates for spawning 

in shallow, densely vegetated areas where the adhesive eggs are broadcast over vegetation (Rosa, 1958; 

Wheeler, 1969; Moyle, 2002; Wydoski and Whitney, 

2003). The Tench is a batch spawner (Moroz, 1968) and 

will spawn over artificial substrates resembling vegetation (Sanchez-Herrera and others, 1998). The species is 

reported to reproduce readily in artificial habitats, for 

example, in some reservoirs in California (Shapovalov, 

1944). Fecundity can be high. In Russia, fecundity 

varied from 280,000-827,000 eggs (Berg, 1964). In the 

Danube, fecundity varied from 25,800-357,210 eggs 

(mean 135,200 eggs; Moroz, 1968). In Poland, fecundity 

ranged from 18,400-416,100 eggs per female (Pimpicka, 

1991). Fecundity increases with body mass and length 

(Moroz, 1968; Pimpicka, 1991). According to Coad 

(2005), the maximum fecundity is 1,241,200 eggs in 

eastern Europe. Eggs are small (1-1.2 mm), yellow or 

green, and hatch in 3-8 days at 22-24 °C (Rosa, 1958; 

Wheeler, 1969). 

Ecology

Within its native range, the Tench grows to 7.5 kg 

(Berg, 1964). Moyle (2002) reported that individuals 

reach sizes of 60-80 cm TL and 2-3 kg in California. 

Wild Tench may live up to 11 years (Neophitou, 1993).

The Tench prefers shallow, vegetated areas of lakes 

and ponds, lower reaches of slow-moving rivers, adjacent backwaters, and oxbow lakes (Berg, 1964; Moroz, 

1968; Wheeler, 1969; O’Maoileidigh and Bracken, 1989; 

Wydoski and Whitney, 2003). Larvae and juveniles 

inhabit areas characterized by dense aquatic vegetation 

(Copp, 1997). During summer months, the Tench seeks 

cooler temperatures by concentrating in deep holes 

and shaded areas (Moyle, 2002). It tends to be inactive during the day, resting in favored habitats such as 

dense aquatic vegetation, and forages for food after dusk 

(Rosa, 1958; Wieser, 1991; Perrow and others, 1996). 

Seeley (1886, p. 140) states: “It is timid, but crafty, 

and comes to the quiet surface of the water only in the 

evening.” 

Figure 52. Tench taken by anglers from two sites in Europe. (A) specimen from Willis’s Lake, a small pond in the suburbs of 

Belfast, Northern Ireland, September 1999. (Photograph courtesy of Robert Rosell.) (B) specimen from a pond in Belgium, 

summer 2004. (Photograph courtesy of Mark Adriaenssens.)

A B

74  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Tench populations are sensitive to loss of vegetated 

habitat and predation pressure. Channelization that 

reduces access to vegetated habitats (such as floodplains) has been associated with a significant reduction 

in juvenile Tench densities (Jurajda, 1995). In a survey 

of >600 Swedish lakes across a wide geographical area, 

population densities were much higher in ponds and 

lakes without piscivores (Brönmark and others, 1995). 

Additionally, population declines were documented in a 

Polish reservoir that became eutrophic (Bnińska, 1991).

The Tench is tolerant of low levels of dissolved 

oxygen, and has been shown to survive oxygen concentrations <1.0 mg/L (Wheeler, 1969; Zhadin and Gerd, 

1963; O’Maoileidigh and Bracken, 1989; Moyle, 2002). 

Rosa (1958) reported that the species survived in waters 

with a low oxygen level that would quickly kill other 

fishes. The 24-hr lethal oxygen concentration was 

experimentally derived as 1.2 mg/L (Kraiem and Pattee, 

1980). Larvae can survive in waters with pH of 5-10, but 

a range of 7-9 is optimal (Hamáčková and others, 1998). 

The Tench is a remarkably hardy fish. Historical 

accounts from England claim fishmongers would bring 

individuals to market and return the unsold fish back 

into water to live (presumably until their next trip to 

market; Seeley 1886). Live Tench have also reportedly 

been shipped during winter in boxes of weeds (Rosa, 

1958). Individuals from northern Europe can withstand 

temperatures near freezing; however, optimal temperature for growth was reported between 12-30 °C (Moyle, 

2002). Rosa (1958) reported that the species burrows 

into the mud during winter for protection against the 

cold where it remains in a motionless condition similar 

to hibernation. The 24-hr upper lethal temperature for 

individuals acclimated to 20 °C was determined to be 

32.3 °C (Kraiem and Pattee, 1980). The species is also 

reported to be tolerant to low levels of salinity. Wheeler 

(1969) reported that the species lives in estuarine conditions in salinities up to 10 ppt in Europe. Moyle (2002) 

reported survival in salinities as high as 12 ppt. Rosa 

(1958) reported that the species is found in brackish 

waters in the Baltic Sea and Tasmania, and calculated a 

24-hr lethal salinity of 15.4 ppt. 

The Tench appears to be a relatively unselective, 

generalist predator of invertebrates (especially benthic 

organisms) in both native and introduced regions. In 

Ireland, Tench <21 cm (in their fourth year or younger) 

fed primarily on plankton, whereas larger and older 

fish consumed mollusks, chironomids, other insects, 

and plankton (O’Maoileidigh and Bracken, 1989). In 

Spain, cladocerans, gastropods, small crustaceans, and 

insect larvae (especially chironomids) and adults were 

preferred prey items (Perez-Bote and others, 1998; 

González and others, 2000). No differences in feeding habits were noted between the sexes (Perez-Bote 

and others, 1998). In Australia, nonindigenous Tench 

consumed chironomids, pulmonate gastropods, cladocerans, amphipods, ephemeropterans, and odonates (Rosa, 

1958). In England and France, Copp and Mann (1993) 

studied food habits of Tench and found that young larvae 

primarily preyed on cladocerans, whereas older larvae 

and 0+ juveniles primarily consumed cladocerans and 

copepods. Giles and others (1990) reported that a population of Tench in the United Kingdom ate a wide variety 

of benthic invertebrates, including bivalves, amphipods, 

isopods, trichopterans, and other insects. Perrow and 

others (1996) reported that Tench fed primarily on 

chironomids. Prejs (1973) documented trichopterans, 

chironomids, mollusks, odonates, and ephemeropterans 

in the diet of Tench from a Polish lake. Brönmark (1994) 

demonstrated that Tench could dramatically reduce the 

biomass of snails and bivalves in enclosures and that 

it also fed heavily on insects and zooplankton. Moyle 

(2002) reported that the diet of small Tench (6-12 cm 

TL) consisted of aquatic insect larvae, especially 

mayflies, damselflies, midges, and caddisflies. Larger 

fish consumed whatever invertebrates were available, 

including snails and oligochaetes (Moyle, 2002). 

Native Distribution

The Tench is native to much of Europe and parts of 

western Asia (Berg, 1964; Coad, 2005).

U.S. Introductions

The Tench was originally imported into North 

America from Germany by the U.S. Fish Commission 

in 1877 and distributed to at least 36 states by 1896. 

Subsequent stocks probably had other origins. For example, at least one other introduced stock was imported 

from Italy (Shapovalov, 1944). Intentional stocking 

and accidental escapes have increased its distribution 

in the U.S. The Tench has been reported in at least 39 

states, but most introductions were unsuccessful, and the 

species has maintained reproducing populations in only a 

few areas (Fuller and others, 1999). Although the species 

was collected in the Richelieu River in the New York/

Quebec area following a recent escape in about 2000, it 

is not yet known to be reproducing in that drainage. 

Tench  75
Ha

waii

Alaska

REPRODUCINGREPORTEDSTATES WITH RECORDS

EXPLANATION

Tench

Tinca tinca

Plate 12. Distribution of Tench in the United States. See Methods for details regarding data used to create maps, definitions of “reproducing” and “reported” and shading of HUCs and states.

76  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
We thank Dr. Petru Bănărescu for his scientific insight and for 

allowing us to reprint his Crucian Carp images. Pingfu Chen assisted 

with Chinese translations. Sherry Bostick and Amy Benson assisted 

in various aspects of the production of the document. The manuscript 

was improved by the reviews of Walt Courtenay, Carter Gilbert, Bob 

Howells, Larry Page, Steve Ross, Todd Slack, and Bill Smith-Vaniz. 

Howard Jelks provided important suggestions. The following individuals kindly provided original photographs: Mark Adriaenssens, 

Richard T. Bryant, Noel Burkhead, Johnny Jensen, Rusty Kimble, 

Fang Fang Kullander, Cathy Mohilo, David Ostendorf, and Robert 

Rosell. Joe Tomelleri provided original artwork for the cover, and 

Vanessa Ramos-Munoz designed it. Lora White at the U.S. Geological 

Survey Leetown Science Center library provided generous assistance with retrieval of literature. Numerous representatives of local, 

state, and federal agencies, as well as many private citizens, industry 

employees, and U.S. and foreign researchers supplied information 

on introduced cyprinid fishes or related subjects. We are grateful for 

their help. The U.S. Fish and Wildlife Service and the U.S. Geological 

Survey provided funding for this project. 

While this report was in press, we became aware of a number 

of new records of foreign nonindigenous cyprinids in the U.S. as 

follows: Carassius auratus (6 additional records), Ctenopharyngodon 

idella (2), Cyprinus carpio (29), Hypophthalmichthys molitrix

(6), Hypophthalmichthys molitrix X nobilis (4), Hypophthalmichthys 

nobilis (2), Tinca tinca (1), and Leuciscus idus (1). 

Most newly acquired records represent occurrences in states or 

drainages already covered in our maps, but a few represent occurrences in drainages not depicted in our maps. Some of these records 

reflect populations that have existed for some time but have only 

recently been reported. Others (such as the Bighead and Silver 

Carp) reflect expansions of these species’ rapidly growing ranges. 

All of the new records reported in this addendum represent species 

already covered in this report. To date (May 2005), no new species of 

foreign cyprinid has become established within the U.S. For details 

of these records and to access the most current information regarding ranges of foreign nonindigenous cyprinids, see our website at: 

http://nas.er.usgs.gov. 

This addendum highlights the dynamic nature of range limits 

of introduced species and the difficulties involved in maintaining 

accurate up-to-date maps of them. 

  77

Acknowledgments

Addendum
Carp for sale in fish market in Shanghai, People’s 

Republic of China, 2004. (Photo by Leo G. Nico.)

78  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
References Cited

Abdusamadov, A.S., 1987, Biology of white amur, Ctenopharyndgodon idella, silver carp, Hypophthalmichthys 

molitrix, and bighead, Aristichthys nobilis, acclimatized in 

the Terek Region of the Caspian Basin: Journal of Ichthyology, v. 26, no. 4, p. 41-49.

Adámek, Z., and Groch, Ladislav, 1993, Morphological adaptations of silver carp (Hypophthalmichthys molitrix Val.) 

lips as a reaction on hypoxic conditions: Folia Zoologica, 

v. 42, no. 2, p. 179-182.

Aho, Jussi, and Holopainen, I.J., 2000, Batch spawning of 

Crucian carp (Carassius carassius [L.]) in mono- and 

multispecies communities: Annales Zoologici Fennici, 

v. 37, p. 101-111.

Aldridge, D.C., 1999, Development of European bitterling 

in the gills of freshwater mussels: Journal of Fish Biology, 

v. 54, no. 1, p. 138-151.

Alikunhi, K.H., and Sukumaran, K.K., 1964, Preliminary 

observations on Chinese carps in India: Proceedings of the 

Indian Academy of Sciences, v. 60, sec. B, p. 171-188.

Aliyev, D.S., 1976, The role of phytophagous fishes in the 

reconstruction of commercial fish fauna and the biological improvement of water: Journal of Ichthyology, v. 16, 

no. 2, p. 216-229.

Al-Mukhtar, M.A., and Al-Hassan, L.A.J., 1999, A natural 

intergeneric hybrid of Barbus sharpeyi (Günther, 1874) 

and Carassius auratus (L.) from a small water body 

in Khoozestan (Iran): Acta Zoologica Bulgarica: v. 51, 

no.1, p. 35-41.

Anderson, R.O., and Neumann, R.M., 1996, Length, weight, 

and associated structural indices, in Murphy, B.R., and 

Willis, D.W., eds., Fisheries techniques (2d ed.): Bethesda, 

Md., American Fisheries Society, p. 447-482. 

Andriasheva, M.A. 1968, Some results obtained by the 

hybridization of cyprinids, in Pillay, T.V.R., ed., Proceedings of the FAO world symposium on warm-water pond 

fish culture, May, 18-25, 1966, Rome, Italy: FAO Fisheries 

Report no. 44, v. 5, p. 205-314.

Aneer, G., and Nellbring, S., 1976, A drop-trap investigation of the abundance of fish in very shallow water in the 

Asko area, northern Baltic, in Benthic Organisms: Oxford, 

Pergamon Press, p. 21-29. 

Antipa, G., 1909, Fauna ihtiologica Romîniei: Bucureşti, 

Adac. Rom., Publ. fond Adamachi, 294 p.

Avault, J.W., Jr., and Merowsky, Andrew, 1978, Evaluation of 

hybrid (common X grass) carp for weed control, in Smitherman, R.O., Shelton, W.L., and Grover, J.H., eds., Symposium on culture of exotic fishes: Auburn, Ala., American 

Fisheries Society, p. 184-193. 

Axlerod, H.R., and Schultz, L.P., 1955, Handbook of tropical 

aquarium fishes: New York, McGraw-Hill Book Company, 

Inc., 718 p.

Bailey, W.M., and Boyd, R.L., 1970, A preliminary report on 

spawning and rearing of grass Carp (Ctenopharyngodon 

idella) in Arkansas, in Proceedings of the 24th Annual 

Conference of the Southeastern Association of Game and 

Fish Commissioners, Atlanta, Ga., September, 27-30, 

1970: p. 560-569.

Bain M.B., Webb, D.H., Tangedal, M.D., and Mangum, L.N., 

1990, Movements and habitat use by grass carp in a large 

mainstream reservoir: Transactions of the American Fisheries Society, v. 119, no. 3, p. 533-561.

Balon, E.K., 1974, Domestication of the carp Cyprinus carpio 

L.: Toronto, Royal Ontario Museum of Life Science, 

Miscellaneous Publications, 37 p.

Balon, E.K., 1995, Origin and domestication of the wild carp, 

Cyprinus carpio: From Roman gourmets to the swimming 

flowers: Aquaculture, v. 129, p. 3-48.

Bănărescu, P., 1964, Fauna republicii populare Romîne—

Pisces-Osteichthyes: Bucuresti, Editura Academiei Republicii Populare Romîne, v. 8, 959 p. [In Romanian.]

Bardach, J.E., Ryther, J.H., and McLarney, W.O., 1972, 

Aquacultur—The farming and husbandry of freshwater and 

marine organisms: New York, Wiley, Interscience, 868 p.

Baruš, Vlastimil, Peaáz, Milan, and Kohlmann, Klaus, 2001, 

Cyprinus carpio (Linnaeus, 1758), in Bănărescu, P.M., 

and Paepke, H.-J., eds., The freshwater fishes of Europe, 

v. 5/III; Cyprinidae 2/III, and Gasterosteidae: AULA-G 

GmbH Wiebelsheim, Germany, p. 85-179.

Battle, H.I. 1940, The embryology and larval development of 

the goldfish (Carassius auratus L.) from Lake Erie: Ohio 

Journal of Science, v. 40, no. 2, p. 82-93.

Beck, M.L., Biggers, C.J., and Dupree, H.K., 1980, Karyological analysis of Ctenopharyngodon idella, Aristichthys 

nobilis, and their F1 hybrids: Transactions of the American 

Fisheries Society, v. 109, no. 4, p. 433-438.

Berg, L.S., 1964, Freshwater fishes in the U.S.S.R. and neighbouring countries, Vol. 2 (4th ed.): IPST Catalog no. 742, 

496 p. [Translated from Russian by Israel Program for 

Scientific Translations, Jerusalem.]

Berry, P.Y., and Low, M.P., 1970, Comparative studies on 

some aspects of the morphology and histology of Ctenopharyngodon idellus, Aristichthys nobilis, and their hybrid 

(Cyprinidae): Copeia, no. 4, p. 708-726.

Bettoli, P.W., Neill, W.H., and Kelsch, S.W., 1985, Temperature preference and heat resistance of grass carp, Ctenopharyngodon idella (Valenciennes), bighead carp, Hypophthalmichthys nobilis (Gray), and their F1

 hybrid: Journal of Fish 

Biology, v. 27, p. 239-247.

References Cited 79
Bianco, P.G., 2004, Threatened fishes of the world: Scardinius 

scardafa (Bonaparte, 1837) (Cyprinidae): Environmental 

Biology of Fishes, v. 71, p. 246.

Bíró, Péter, 1999, Mylopharyngodon piceus (Richardson, 

1846), in Bănărescu, P., ed., The freshwater fishes of 

Europe, v. 5/I, Cyprinidae 2/I: Wiebelshiem, Germany, 

AULU-Verlag, p. 347-365.

Bnińska, M., 1991, Fisheries, in Winfield, I.J., and Nelson, 

J.S., eds., Cyprinid fishes: Systematics, biology and exploitation: London, Chapman and Hall, p. 572-589.

Bochung, Herbert T., Jr,. and Mayden, R.L., 2004, Fishes of 

Alabama: Washington, Smithsonian Institution Press.

Bogutskaya, N.G., 1997, Contribution to the knowledge of 

leuciscine fishes of Asia Minor, Part 2. An anotated checklist of leuciscine fishes (Leuciscinae, Cyprinidae) of Turkey 

with descriptions of a new species and two new subspecies: Mitteilungen aus dem Hamburgischen Zoologischen 

Museum und Institut, v. 94, p. 161-186. 

Bonar, S.A., Thomas, G.L., and Pauley, G.B., 1988, Evaluation of the separation of triploid and diploid grass carp, 

Ctenopharyngodon idella (Valenciennes), by external 

morphology: Journal of Fish Biology, v. 33, p. 895-898.

Bracken, J.J., and Kennedy, M.P., 1967, A key to the eggs 

and young stages of course fish in Irish waters: Science 

Proceedings of the Royal Dublin Society, v. 2, no. 12, 

p. 99-108.

Breder, C.M., 1933, Rhodeus amarus spawning in American 

mussels: Copeia, p. 147-148.

Britz, Ralf, 2003, Danionella mirifica, a new species of miniature fish from Upper Myanmar (Ostariophysi: Cyprinidae): 

Ichthyological Explorations of Freshwaters v. 14, no. 3, 

p. 217-222.

Brönmark, Christer, 1994, Effects of tench and perch on interactions in a freshwater, benthic food chain: Ecology, v. 75, 

no. 6, p. 1818-1828.

Brönmark, C., Paszkowski, C.A., Tonn, W.M., and Hargeby, 

A., 1995, Predation as a determinant of size structure in 

populations of Crucian carp (Carassius carassius) and tench 

(Tinca tinca): Ecology of Freshwater Fish, v. 4, p. 85-92.

Burke, J.S., Bayne, D.R., and Rea, Harry, 1986, Impact of 

silver and bighead carps on plankton communities of channel catfish ponds: Aquaculture, v. 55, p. 59-68.

Burkhead, N.M., and Williams, J.D., 1991, An intergeneric 

hybrid of a native minnow, the golden shiner, and an exotic 

minnow, the rudd: Transactions American Fisheries Society, 

v. 120, no. 6, p. 781-795.

Cadwallader, P.L., 1977, Introduction of rudd Scardinius 

erythropthalmus into New Zealand. I—Review of the ecology of rudd and the implications of its introduction into 

New Zealand: Ministry of Agriculture and Fisheries, Fisheries Technical Report no. 47. 

Cala, Plutarco, 1970, On the ecology of the ide Idus idus (L.) 

in the River Kävlingeån, South Sweden: Drottningholm, 

Sweden, Report of the Institute of Freshwater Research, 

v. 50, p. 46-99.

Cala, Plutarco, 1971, Size and age at maturity, ripening and 

fecundity of the ide Idus idus (L.): Drottningholm, Sweden, 

Report of the Institute of Freshwater Research, v. 51, 

p. 31-46.

Cala, Plutarco, 1976, Age at maturity, testicular development and seasonal changes in the testes of the ide Idus idus 

(L.) (Pisces, Cyprinidae) in the River Kävlingeån, South 

Sweden: Drottningholm, Sweden, Report of the Institute of 

Freshwater Research, v. 55, p. 5-14.

Calliet, G.M., Love, M.S., and Ebeling, A.W., 1986, Fishes: 

A field and laboratory manual on their structure, identification, and natural history: Prospect Heights, Ill., Waveland 

Press.

Canagaratnam, P., 1959, Growth of fishes in different salinities: Journal of the Fisheries Research Board of Canada, 

v. 16, no. 1, p. 121-130.

Carlander, K.D., 1969, Handbook of freshwater fishery biology: Ames, Iowa State University Press, v. 1, 752 p.

Cassani, J.R., ed., 1996, Managing aquatic vegetation with 

grass carp: A guide for water resource managers: Bethesda, 

Md., American Fisheries Society, 196 p.

Cassani, J.R., Caton, W.D., and Clark, B., 1984, Morphological comparisons of diploid and triploid hybrid grass 

carp, Ctenopharyngodon idella (♀) X Hypophthalmichthys 

nobilis (♂): Journal of Fish Biology, v. 25, p. 269-278.

Černý, Karel, 1977, The early development of chub–Leuciscus cephalus (L., 1758), rudd–Scardinius erythrophthalmus (L., 1758), and roach–Rutilus rutilus (L., 1758): Acta 

Universitatis Carolinae–Biologica, v. 1-2, p. 1-149.

Chang, Y.F., 1966, Culture of freshwater fish in China: 

Beijing, Science Publishers. [Translated from Chinese to 

English by Koo, Ted S.Y., Department of Fisheries, U.S. 

Department of Interior; edited by Gangstad, E.O., Department of the Army, Washington, D.C. Draft of translation 

(January 1980) available as: Chinese fish culture: Report 1 

of a series. Technical report A-79-#. Aquatic Plant Control 

Research Program. Prepared for Office, Chief of Engineers, 

U.S. Army, Washington, D.C.]

Chen, Ning-Shen, and Chuan-Fang Shih, 1955, Oxygen 

consumption of Ctenopharyngodon idellus, Hypophthalmichthys molitrix, and Aristichthys nobilis: Acta Zoologica 

Sinica, v. 7, no. 1, p. 42-57. [In Chinese with English 

summary and content.]

Chen, Y. ed., 1998, Fauna Sinica, Osteichthyes, Cypriniformes 

II: Beijing, Science Press, 531 p. [In Chinese.]

80 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Chervinski, Jonathan, 1977, Note on the adaptability of 

silver carp–Hypophthalmichthys molitrix (Val.), and grass 

carp–Ctenopharyngodon idella (Val.), to various salinities: 

Aquaculture, v. 11, p. 179-182.

Chervinski, Jonathan, 1980, Note on the adaptability of bighead (Aristichthys nobilis) to various saline concentrations: 

Israeli Journal of Aquaculture (Bamidgeh), v. 32, no. 1, 

p. 27-29.

Chick, J.H., Maher, R.J., Burr, B.M., Thomas, M.R., 2003, 

First black carp captured in the U.S: Science 300, p. 1876-

1877. 

Chilton, E.W., II, and Muoneke, M.I., 1992, Biology and 

management of grass carp (Ctenopharyngodon idella, 

Cyprinidae) for vegetation control: A North American 

perspective: Reviews in Fish Biology and Fisheries, v. 2, 

p. 283-320.

Chu (= Zhu), Xinluo, Yinrui Chen, and others, 1989, The 

fishes of Yunnan, China, Part I. Cyprinidae: Beijing, 

Science Press. [In Chinese.] 

Clugston, J.P., and Shireman, J.V., 1987, Triploid grass carp 

for aquatic plant control: U.S. Fish and Wildlife Service, 

Leaflet 8, 3 p.

Coad, B.W., 2005, Freshwater fishes of Iran: Species 

Accounts—Cyprinidae (revised January 14, 2005): URL 

http://www.briancoad.com/Species%20Accounts/cyprinidae.htm.

Coates, G.D., and Turner, A.S., 1977, Introduction of rudd 

Scardinius erythrophthalmus into New Zealand, Vol. 2. First 

survey of a rudd population in New Zealand: Ministry of 

Agriculture and Fisheries, Fisheries Technical Paper no. 47. 

Collee, D.E., Shireman, J.V., and Rottmann, R.W., 1978, Food 

selection by grass carp fingerlings in a vegetated pond: 

Transactions of the American Fisheries Society, v. 107, 

no. 1, p. 149-152.

Copp, G.H., 1997, Microhabitat use of fish larvae and 0+ 

juveniles in a highly regulated section of the River Great 

Ouse: Regulated Rivers Research and Management, v. 13, 

p. 267-276.

Copp, G.H., and Mann, R.H.K., 1993, Comparative growth 

and diet of tench Tinca tinca (L.) larvae and juveniles from 

river floodplain biotopes in France and England: Ecology of 

Freshwater Fish, v. 2, no. 2, p. 58-66.

Courtenay, W.R., Jr., Hensley, D.A., Taylor, J.N., and McCann, 

J.A., 1984, Distribution of exotic fishes in the continental 

United States, in Courtenay, W.R., Jr., and Stauffer, J.R., 

Jr., eds., Distribution, biology, and management of exotic 

fishes: Baltimore, Johns Hopkins University Press, p. 41-77. 

Courtenay, W.R., Jr., and Stauffer, J.R., Jr., 1990, The introduced fish problem and the aquarium fish industry: Journal 

of the World Aquaculture Society, v. 21, no. 3, p. 145-159.

Cremer, M.C., and Smitherman, R.O., 1980, Food habits 

and growth of silver and bighead carp in cages and ponds: 

Aquaculture, v. 20, p. 57-64.

Crivelli, A.J., 1981, The biology of the common carp, Cyprinus carpio L. in Camargue, southern France: Journal of Fish 

Biology, v. 18, p. 271-290.

Cross, D.G., 1970, The tolerance of grass carp Ctenopharyngodon idella (Val.) to seawater: Journal of Fish Biology, 

v. 2, p. 231-233.

De Kay, J.E., 1842, Zoology of New-York, or the New-York 

fauna, Part IV: W. and A. White (sic), and Visscher, J., 

Fishes: Albany, N.Y., 415 p, 79 plates.

Dence, W.A., 1925, Bitter carp (Rhodeus amarus) from New 

York State waters: Copeia, no. 142, 33 p.

Dill, W.A., and Cordone, A.J., 1997, History and status of 

introduced fishes in California, 1871-1996: California 

Department of Fish and Game, Fish Bulletin178, 1-414 p.

Domaizon, Isabelle, and Devaux, Jean, 1999, Experimental 

study of the impacts of silver carp on plankton communities 

of eutrophic Villerest reservoir (France): Aquatic Ecology, 

v. 33, p. 193-204.

Dong, Shuanglin, and Li, Deshang, 1994, Comparative studies 

on the feeding selectivity of silver carp Hypophthalmichthys 

molitrix and bighead carp Aristichthys nobilis: Journal of 

Fish Biology, v. 44, p. 621-626.

Eder, Stephen, and Carlson, C.A., 1977, Food habits of carp 

and white suckers in the South Platte and St. Vrain Rivers 

and Goosequill Pond, Weld County, Colorado: Transactions 

of the American Fisheries Society, v. 106, no. 4, p. 339-349.

Edwards, D.J., 1973, Aquarium studies on the consumption 

of small animals by 0-group grass carp, Ctenopharyngodon 

idella (Val.): Journal of Fish Biology, v. 5, p. 599-605.

Eschmeyer, W.N., Ferraris, C.J., Jr., Mysi Dang Hoang, and 

Long, D.J., 1998, A catalogue of the species of fishes 

[Preliminary Version 2, November 1996]: California Academy of Sciences, URL http://www.calacademy.org/research/

ichthyology/species/.

Etnier, D.A., and Starnes, W.C., 1993, Fishes of Tennessee: 

Knoxville, University of Tennessee Press, 681 p.

Evtushenko, N.Y., Potrokhov, A.S., and Zinkovskii, O.G., 

1994, The black carp as a subject for acclimatization 

(review): Hydrobiological Journal, v. 30, no. 5, p. 1-10. 

[Originally published in Russian in 1993: Gidrobiologicheskiy Zhurnal, v. 29, no. 3, p. 49-56.]

Florez, Fabio, 1972a, The effect of temperature on incubation 

time, growth and lethality of embryos, larvae and juveniles 

of the ide, Idus idus (L.): Drottningholm, Sweden, Report of 

the Institute of Freshwater Research, v. 52, p. 50-60.

References Cited 81
Florez, Fabio, 1972b, Influence of oxygen concentration on 

growth and survival of larvae and juveniles of the ide, Idus 

idus (L.): Drottningholm, Sweden, Report of the Institute of 

Freshwater Research, v. 52, p. 65-73.

Forester, J.S., and Avault, J.W., Jr., 1978, Effects of grass carp 

on freshwater red swamp crayfish in ponds: Transactions of 

the American Fisheries Society, v. 107, no. 1, p. 156-160.

Freeze, Mike, and Henderson, Scott, 1982, Distribution and 

status of the bighead carp and silver carp in Arkansas: 

North American Journal of Fisheries Management, v. 2, 

p. 197-200.

Fuller, P.L., Nico, L.G., and Williams, J.D., 1999, Nonindigenous fishes introduced into inland waters of the United 

States: Bethesda, Md., American Fisheries Society, Special 

Publication 27, 613 p.

Garcia, L.M.B., Garcia, C.M.H., Pineda, A.F.S., Gammad, 

E.A., Canta, J., Simon, S.P.D., Hilomen-Garcia, G.V., 

Gonzal, A.C., and Santiago, C.B., 1999, Survival and 

growth of bighead carp fry exposed to low salinities: Aquaculture International, v. 7, p. 241-250.

Gasaway, R.D., and Drda, T.F., 1977, Effects of grass carp 

introduction on waterfowl habitat: Transactions of the 42nd

North American Wildlife and Natural Resources Conference: Washington, D.C., Wildlife Management Institute, 

p. 73-85.

Gerlach, J.M., 1983, Characters for distinguishing larval carp, 

Cyprinus carpio, and goldfish, Carassius auratus: Copeia, 

v. 1, p. 116-121.

Giles, N., Street, M., and Wright, R.M., 1990, Diet composition and prey preference of tench, Tinca tinca (L.), common 

bream, Abramis brama (L.), perch, Perca fluviatilis (L.), 

and roach, Rutilus rutilus (L.), in two contrasting gravel pit 

lakes: Potential trophic overlap with wildfowl: Journal of 

Fish Biology, v. 37, p. 945-957.

González, Gustavo, Mazé, R.A., Domínguez, Josefa, and 

Pena, J.C., 2000, Trophic ecology of the tench, Tinca tinca 

in two different habitats in North-West of Spain: Cybium, 

v. 24, no. 2, p. 123-138.

Gorbach, E.I., 1961, Age composition, growth and age of 

onset of sexual maturity of the white Ctenopharyngodon idella (Val.) and the black Mylopharyngodon piceus

(Rich.) amurs in the Amur River basin: Vopr. Ikhtiol, v. 1, 

p. 119-126.

Gorbach, E.I., 1972, Fecundity of the grass carp (Ctenopharyngodon idella [Val.]) in the Amur basin: Journal of 

Ichthyology, v. 12, p. 616-625.

Green B.W., and Smitherman, R.O., 1984, Relative growth, 

survival and harvestability of bighead carp, silver carp, and 

their reciprocal hybrids: Aquaculture, v. 37, p. 87-95.

Gulyás, Pál, and Fleit, Ernö, 1990, Evaluation of ammonia 

toxicity on Daphnia magna and some fish species: Aquacultura Hungarica (Szarvas), v. 6, p. 171-183. 

Hamáčková, Jitka, Kouřil, Jan, and Kozák, Pavel, 1998, The 

effects of pH upon survival and growth rates in tench (Tinca 

tinca [L.]) larvae: Polskie Archiwum Hydrobiologii, v. 45, 

no. 3, p. 399-405.

Hartley, P.H.T., 1947, The natural history of some British 

freshwater fishes: Proceedings of the Zoological Society of 

London, v. 117, p. 129-206.

Hellawell, J.M., 1986, Biological indicators of freshwater 

pollution and environmental management: London, Elsevier 

Applied Science, 546 p.

Hensley, D.A., and Courtenay, W.R., Jr., 1980, Carassius 

auratus (Linnaeus), goldfish, in Lee, D.W., Gilbert, C.R., 

Hocutt, C.H., Jenkins, R.E., McAllister, D.E., and Stauffer, 

J.R., Jr., eds., Atlas of North American freshwater fishes: 

Raleigh, North Carolina State Museum of Natural History, 

p. 147.

Hickling, C.F., 1967, On the biology of a herbivorous fish, the 

white amur or grass carp, Ctenopharyngodon idella Val.: 

Proceedings of the Royal Society of Edinburgh, v. 70B, 

pt. 1, p. 62-81.

Holčík, Juraj, 1967, Life history of the rudd Scardinius 

erythrophthalmus (Linnaus, 1958) in the Klíčava Reservoir: 

Vĕstník Československé Společnosti Zoologické, v. 31, 

no. 4, p. 335-348. 

Holčík, Juraj, and Jedlička, Ladislav, 1994, Geographical 

variation of some taxonomically important characters in 

fishes: The case of the bitterling Rhodeus sericeus: Environmental Biology of Fishes, v. 41, no. 1-4, p. 147-170.

Holopainen, I.J., Aho, J., Vornanen, M., and Huuskonen, 

H., 1997, Phenotypic plasticity and predator effects on 

morphology and physiology of Crucian carp in nature and 

in the laboratory: Journal of Fish Biology, v. 50, p. 781-798.

Holopainen, I.J., and Hyvärinen, H., 1984, Ecology and physiology of Crucian carp (Carassius carassius L.) in small 

Finnish ponds with anoxic conditions in winter. Verhandlungen: Internationale Vereiningung fur theoretische und 

angewandte Limnology, v. 22, no. 4, p. 2566-2570.

Howells, R.G., 1992, Guide to identification of harmful and 

potentially harmful fishes, shellfishes, and aquatic plants 

prohibited in Texas: Austin, Texas Parks and Wildlife 

Department, Special Publication, 182 p., 88 apps.

Howells, R.G., 1999, Guide to identification of harmful and 

potentially harmful fishes, shellfishes, and aquatic plants 

prohibited in Texas (revised): Austin, Texas Parks and 

Wildlife Department, Special Publication of the Fisheries 

Division, 370 p.

Hubbs, C.L., and Lagler, K.F., 1958, Fishes of the Great Lakes 

region: Cranbrook Institute, Scientific Bulletin 26, 213 p.

Huet, Marcel, 1970, Textbook of fish culture: Breeding and 

cultivation of fish: London, Fishing News (Books) Ltd., 

536 p.

82  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Hume, D.J., Fletcher, A.R., and Morison, A.L., 1983, Interspecific hybridization between carp (Cyprinus carpio L.) 

and goldfish (Carassius auratus L.) from Victorian waters: 

Australian Journal of Marine and Freshwater Research, 

v. 34, p. 915-919.

Hynes, H.B.N., 1970, The ecology of running waters: University of Toronto Press, 555 p.

IGFA [International Game Fish Association], 2001, Database 

of IGFA angling records until 2001: Fort Lauderdale, Fla.

Iguchi, Kei’ichiro, Yamamoto, Gunji , Matsubara, Naoto, 

and Nishida, Mutsumi, 2003, Morphological and genetic 

analysis of fish of a Carassius complex (Cyprinidae) in 

Lake Kasumigaura with reference to the taxonomic status 

of two all-female triploid morphs: Biological Journal of the 

Linnean Society, v. 79, no. 2, p. 351-357.

Jenkins, R.E., and Burkhead, N.M., 1994, Freshwater fishes 

of Virginia: Bethesda, Md., American Fisheries Society, 

1079 p.

Jennings, Dawn, 1988, Bighead carp (Hypophthalmichthys nobilis): Biological synopsis. U.S. Fish and Wildlife 

Service, Biological Report, v. 88, no. 29, 47 p.

Jevtić, Jelena, 1979, Number of spine vertebrae in the populations of tench [Tinca tinca L.]: Ichthyologia, v. 11, no. 1, 

p.15-18. [In Serbo-Croation with English summary.]

Jones, J.W., and Linfield, R.S.J., 1972, A note on the identification of a Crucian carp Carassius carassius (L.) x common 

carp Cyprinus carpio (L.) hybrid from a still water in 

Nottinghamshire: Journal of Fish Biology, v. 4, p. 309-310. 

Jones, P.W., Martin, F.D., and Hardy, J.D., Jr., 1978, Development of fishes of the Mid-Atlantic Bight, Vol. I. Acipenseridae through Ictaluridae: U.S. Fish and Wildlife Service, 

Biological Services Program, FWS/OBS-78/12, 366 p.

Jurajda, Pavel, 1995, Effect of channelization and regulation 

on fish recruitment in a flood plain river: Regulated Rivers 

Research and Management, v. 10, p. 207-215.

Jurajda, Pavel, 1998, Drift of larval and juvenile fishes, 

especially Rhodeus sericeus and Rutilus rutilus, in the River 

Morava (Danube Basin): Archiv für Hydrobiologie, v. 141, 

no. 2, p. 231-241.

Kamilov, B.G., and Komrakova, M.Y., 1999, Maturation and 

fecundity of the silver carp, Hypophthalmichthys molitrix, 

in Uzbekistan: Israeli Journal of Aquaculture (Bamidgeh), 

v. 51, no. 1, p. 40-43.

Kasama, Midoriko, and Kobayasi, Hiromu, 1989, Hybridization experiment between female Crucian carp and male 

grass carp: Nippon Suisan Gakkaishi, v. 55, no. 6, p. 1001-

1006.

Kasama, Midoriko, and Kobayasi, Hiromu, 1990, Hybridization experiment between Carassius carassius (♀) and 

Gnathopogon elongatus elongatus (♂): Japanese Journal of 

Ichthyology, v. 36, no. 4, p. 419-426.

Kennedy, M., and Fitzmaurice, P., 1974, Biology of the rudd 

Scardinius erythropthalmus (L.) in Irish waters: Proceedings of the Royal Irish Academy, 74, sec. B, no. 18.

Kilambi, R.V., and Zdinak, A., 1980, The effects of acclimation on the salinity tolerance of grass carp, Ctenopharyngodon idella (Cuv. and Val.): Journal of Fish Biology, v. 16, 

p. 171-175.

Kilambi, R.V., and Zdinak, A., 1981, Comparison of early 

developmental stages and adults of grass carp (Ctenopharyngodon idella) and hybrid carp (female grass carp X male 

bighead Aristichthys nobilis): Journal of Fish Biology, v. 19, 

p. 457-465.

Kilambi, R.V., and Zdinak, A., 1982. Food intake and growth 

of hybrid carp (female grass carp, Ctenopharyngodon idella 

X male bighead, Aristichthys (Hypophthalmichthys) nobilis) 

fed on zooplankton and Chara: Journal of Fish Biology, 

v. 21, p. 63-37.

Kilgen, R.H., and Smitherman, R.O., 1971, Food habits of the 

white amur stocked in ponds alone and in combination with 

other species: The Progressive Fish-Culturist, v. 33, no. 3, 

p. 123-127.

Kimura, S., 1934, Description of the fishes collected from 

the Yangtze-kiang, China, by late Dr. K. Kishinouye and 

his party in 1927-1929: Shanghai, Journal of the Shanghai 

Science Institute, section 3, v. 1, p. 11-247.

Kimura, Shigeru, and Yusan Tao, 1937, Notes on the nuptial 

coloration and pearl organs in Chinese fresh-water fishes. 

Report no. 1. Biological studies on Chinese freshwater 

fishes. Report no. 4: Journal of the Shanghai Science 

Institute, v. 6, p. 277-318. [Translated from Chinese by 

Tchaw-ren Chen and edited by Bruce B. Collette.] Translation no. 66, Bureau of Commercial Fisheries, Systematics 

Laboratory, U.S. National Museum, Washington, D.C.

King, D.R., and Hunt, G.S., 1967, Effect of carp on vegetation in a Lake Erie marsh: Journal of Wildlife Management, 

v. 31, no. 1, p. 181-188.

Korniyenko, G.S., 1971, The role of infusoria in the food of 

the larvae of phytophagous fishes: Journal of Ichthyology, 

v. 11, no. 2, p. 241-246.

Koutrakis, E.T., Kokkinakis, A.K., Tsikliras, A.C., and 

Eleftheriadis, E.A., 2003, Characteristics of the European 

bitterling Rhodeus amarus (Cyprinidae) in the Rihios 

River, Greece: Journal of Freshwater Ecology, v. 18, no. 4, 

p. 615-624.

Kraiem, M., and Pattee, E., 1980, Temperature and oxygen 

deficiency tolerance of the barbel [Barbus barbus L.] and 

three other species: Archiv für Hydrobiologie, v. 88, no. 2, 

p. 250-261. [In French with English summary.]

Krykhtin, M.L., and Gorbach, E.I., 1981, Reproductive ecology of the grass carp, Ctenopharyngodon idella, and the 

silver carp, Hypophthalmichthys molitrix, in the Amur 

Basin: Journal of Ichthology, v. 21, no. 2, p. 109-123.

References Cited 83
Kuronuma, K., 1968, New systems and new fishes for culture 

in the Far East, in Pillay, T.V.R., ed., Proceedings of the 

FAO world symposium on warm-water pond fish culture, 

18-25 May, 1966: Rome, Italy, FAO Fisheries Report, v. 44, 

no. 5, p. 123-142.

Laird C.A., and Page, L.M., 1996, Non-native fishes inhabiting the streams and lakes of Illinois: Illinois Natural History 

Survey, Bulletin, v. 35, article 1, 51 p.

Lammens, E.H.R.R., and Hoogenboezem, W., 1991, Diets 

and feeding behaviour, in Winfield, I.J., and Nelson, J.S., 

eds., Cyprinid fishes: Systematics, biology and exploitation: 

London, Chapman and Hall, p. 353-376.

Laurila, Sari, and Holopainen, I.J., 1990, Features of embryonic and larval development of Crucian carp Carassius 

carassius (L.) with a note on species identification: Annales 

Zoologici Fennici, v. 27, p. 361-367.

Laurila, Sari, Piironen, Jorma, and Holopainen, I.J., 1987, 

Notes on egg development and larval and juvenile growth 

of Crucian carp (Carassius carassius [L.]): Annales Zoologici Fennici, v. 24, p. 315-321.

Laws, E.A., and Weisburd, R.S.J., 1990, Use of silver carp to 

control algal biomass in aquaculture ponds: The Progressive 

Fish-Culturist, v. 52, no. 1, p. 1-8.

Lazzaro, Xavier, 1987, A review of planktivorous fishes: Their 

evolution, feeding behaviours, selectivities, and impacts: 

Hydrobiologia, v. 146, p. 97-167.

Leventer, H., 1979, Biological control of reservoirs by fish: 

Nazareth Elit, Israel, Mekoroth Water Co., Jordan District 

Central Laboratory of Water Quality, 71 p.

Lever, C., 1996, Naturalized fishes of the world: Academic 

Press, 408 p.

Li, Sifa, and Mathias, Jack, eds., 1994, Freshwater fish culture 

in China: Principles and practice: Amsterdam, Elsevier, 

445 p.

Li, Sizhong, and Fang Fang, 1990, On the geographical distribution of the four kinds of pond-cultured carps in China: 

Acta Zoologica Sinica, v. 36, no. 3, p. 244-250. [In Chinese 

with English abstract.]

Li, Xinfu, and Fuying Zhang, 1992, Toxic effects of low pH 

and elevated Al concentration on early life stages of several 

species of freshwater fishes: Acta Scientiae Circumstantiae, 

v. 12, no. 1, p. 97-104. [In Chinese with English summary.]

Liang, Xiuquin, and Fuling Wang, 1993, An approach to the 

problem of water chemical factors and fishery utilization in 

alkaline waters: Journal of Dalian Fisheries College, v. 8, 

no. 4, p. 67-72. [In Chinese with English summary.]

Lin, H.R., and Peter, R.E., 1991, Aquaculture, in Winfield, I.J., 

and Nelson, J.S., eds., Cyprinid fishes: Systematics, biology 

and exploitation: London, Chapman and Hall p. 590-622.

Lippson, A.J., and Moran, R.L., 1974, Manual for identification of early developmental stages of fishes of the Potomac 

River estuary: Annapolis, Md., Power Plant Siting Program, 

Maryland Department of Natural Resources, Special Publication PPSP-MP-13. 

Lirski, Andrzej, and Opuszyński, Karol, 1988a, Lower lethal 

temperatures for carp [Cyprinus carpio L.] and the phytophagous fishes [Ctenopharyngodon idella Cal., Hypophthalmichthys molitrix Val., Aristichthys nobilis Rich.] in the first 

period of life: Roczniki Nauk Rolniczych, v. 101, p. 11-29. 

[In Polish with English summary.]

Lirski, Andrzej, and Opuszyński, Karol, 1988b, Upper lethal 

temperatures for carp [Cyprinus carpio L.] and the phytophagous fishes [Ctenopharyngodon idella Val., Hypophthalmichthys molitrix Val., Aristichthys nobilis Rich.] in the 

first period of life: Roczniki Nauk Rolniczych, v. 101, no. 4, 

p. 31-49. [In Polish with English summary.]

Liu, Huanliang, Hua Li, Baoxiang Zhai, and Wei Liu, 1990, 

Post-larval development of the masticating apparatus of 

black carp Mylopharyngodon piceus [Richardson]: Acta 

Hydrobiologica Sinica, v. 14, no. 4, p. 310-320. [In Chinese 

with English summary.]

Lockley, A.S., 1957, Adrenal cortical hormones and osmotic 

stress in three species of fishes: Copeia, no. 3, p. 241-242.

Lubinski, K.S. VanVooren, A., Farabee, G., Janecek, J., and 

Jackson, S.D., 1986, Common carp in the Upper Mississippi 

River: Hydrobiologia, v. 136, p. 141-153.

Maceina, M.J., Bettoli, P.W., Klussman, W.G., Betsill, R.K., 

and Noble, R.L., 1991, Effect of aquatic macrophyte 

removal on recruitment and growth of black crappies and 

white crappies in Lake Conroe, Texas: North American 

Journal of Fisheries Management, v. 11, no. 4, p. 556-563.

Maceina, M.J., Nordlie, F.G., and Shireman, J.V., 1980, The 

influence of salinity on oxygen consumption and plasma 

electrolytes in grass carp, [Ctenopharyngodon idella Val]: 

Journal of Fish Biology, v. 16, p. 613-619.

Maceina, M.J., and Shireman, J.V., 1979, Grass carp: Effects 

of salinity on survival, weight loss and muscle tissue 

water content: The Progressive Fish-Culturist, v. 41, no. 2, 

p. 69-73.

Maceina, M.J., and Shireman, J.V., 1980, Effects of salinity 

on vegetation consumption and growth in grass carp: The 

Progressive Fish-Culturist, v. 42, no. 1, p. 50-53.

Maitland, P.S., 1977, The Hamlyn guide to freshwater fishes 

of Britain and Europe: London, Hamlyn Publishers, 256 p.

Makeyeva, A.P., 1968, Hybridization of the common carp with 

phytophagous fishes: Problems in Ichthyology, v. 8, no. 2, 

p. 294-297.

Makeyeva, A.P., 1972, Hybridization of the bighead (Aristichthys nobilis [Rich.]) and the carp (Cyprinus carpio L.): 

Journal of Ichthyology, v. 12, no. 2, p. 274-282.

84  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Makeyeva, A.P., 1975, The phenomenon of hybrid gynogenesis in fishes: Journal of Ichthyology, v. 15, no. 1, p. 72-81.

Makeyeva, A.P., and Verigin, B.V., 1993, Morphological characters of age 0+ reciprocal hybrids of grass carp, Ctenopharyngodon idella and black carp, Mylopharyngodon piceus: 

Journal of Ichthyology, v. 33, no. 3, p. 66-75.

Makeyeva, A.P., and Verigin, B.V., 1974a, Hybridization of the 

pond carp (Cyprinus carpio) with the grass carp (Ctenopharyngodon idella): Journal of Ichthyology, v. 14, p. 254-259.

Makeyeva [Makeeva], A.P., and Verigin, B.V., 1974b, A hybrid 

between common carp and silver carp: Genetika, v. 10, 

no. 2, p. 73-80. [In Russian with English summary.]

Márián, Teréz, and Krasznai, Zoltán, 1978, Kariological 

investigations on Ctenopharyndogon idella and Hypophthalmichthys nobilis and their cross-breeding: Aquacultura 

Hungarica (Szarvas), v. 1, p. 44-50.

McCrimmon, H.R., 1968, Carp in Canada: Fisheries Research 

Board of Canada, Bulletin 165, 93 p.

Meek, S.E., and Hildebrand, S.F., 1910, A synoptic list of the 

fishes known to occur within fifty miles of Chicago: Field 

Museum of Natural History, Publication 142, Zoological 

Series, v. 7, no. 9, p. 223-338.

Mihai-Bardan, Alina, 1980, Données concernant le développement embryonnaire des hybrides résultés du croisement entre Hypophthalmichthys molitrix (Valenciennes, 

1844) et Aristichthys nobilis (Richardson, 1844) (Osteichthyes, Cyprinidae): Travaux Museum d’Histoire Naturelle 

“Grigore Antipa,” v. 21, p. 205-212. [In French with 

Romanian summary.]

Mills, S.C., and Reynolds, J.D., 2002, Mussel ventilation rates 

as a proximate cue for host selection by bitterling, Rhodeus 

sericeus: Oecologica, v. 131, no. 3, p. 473-378.

Minckley, W.L., 1973, Fishes of Arizona: Phoenix, Sims 

Printing Company, 293 p.

Mitzner, Larry, 1978, Evaluation of biological control of 

nuisance aquatic vegetation by grass carp: Transactions of 

the American Fisheries Society, v. 107, no. 1, p. 135-145.

Moroz, V.N., 1968, Biology of the tench Tinca tinca (L.) in the 

Kiliya Channel, Danube Delta: Problems of Ichthyology, 

v. 8, no. 1, p. 81-89.

Moyle, P.B., 2002, Inland fishes of California (2d ed.): 

Berkeley, University of California Press, 502 p.

Murai, Takeshi, and Andrews, J.W., 1977, Effects of salinity 

on the eggs and fry of the golden shiner and goldfish: The 

Progressive-Fish Culturist, v. 39, no. 3, p. 121-122.

Mutenia, Ahti, 1978, On the biology of the ide (Leuciscus idus

L.) in Lokka reservoir, Finnish Lapland): Luonnon Tutkija, 

v. 82, p.135-137. [In Finnish with English summary.]

Muus, B.J., 1971, Freshwater fish of Britain and Europe: 

London , Collins, 222 p.

Myers, G.S., 1925, Introduction of the European bitterling 

(Rhodeus) in New York and of the rudd (Scardinius) in New 

Jersey: Copeia no. 140, p. 20-21.

Nakamura, Morizumi, 1963, Keys to the freshwater fishes 

of Japan fully illustrated in colors: Hokuryukan, Japan, 

258 p. [In Japanese with English summary.]

Nakamura, Morizumi, 1969, Cyprinid fishes of Japan: Studies on the life history of cyprinid fishes of Japan: Tokyo, 

Japan, Special Publications of the Research Institute 

for Natural Resources, no. 4 (Contribution no. 1198), 

455 p. [In Japanese with English summary.]

Negonovskaya, I.T., and Rudenko, G.P., 1974, The oxygen 

threshold and characteristics of the respiratory metabolism 

of juvenile herbivorous fishes—The grass carp and the 

bighead: Journal of Ichthyology, v. 14, no. 6, p. 965-970.

Nelson, J.S., 1994, Fishes of the world, (3rd ed.): New York, 

John Wiley, 600 p.

Nelson, J.S., Crossman, E.J., Espinosa-Perez, Hector, Findley, 

L.T., Gilbert, C.R., Lea, R.N., and Williams, J.D., 2004, 

Common and scientific names of fishes from the United 

States, Canada, and Mexico (6th ed.): Bethesda, Md., American Fisheries Society, Special Publication no. 29, 386 p.

Neophitou, Christos, 1993, Some biological data on tench 

(Tinca tinca [L.]) in Lake Pamvotida (Greece): Acta 

Hydrobiologia, v. 35, no. 4, p. 367-379.

Nico, L.G., 2005, Changes in the fish fauna of the Kissimmee River basin, peninsular Florida: Non-Native Additions, in Rinne, J.N., Hughes, R.M., and Calamusso, B., 

(eds.), Historical changes in large river fish assemblages 

of America: Bethesda, Md., American Fisheries Society 

Symposium, in press.

Nico, L.G., Williams, J.D., and Jelks, H.L., 2005, Black carp: 

Biological synopsis and risk assessment of an introduced 

fish: Bethesda, Md., American Fisheries Society Special 

Publication 32.

Nikolsky (= Nikol’skii), G.V., 1956, Fishes of the Amur River 

Basin: Results of the Amur River Ichthyological Expedition 

of 1945-1949: Moscow, USSR Academy of Sciences Press, 

Moscow. [In Russian.]

Nikolsky [=Nikol’skiy], G.V., and Aliyev, D.D., 1974, The 

role of far-eastern herbivorous fishes in the ecosystems of 

natural waters in which they are acclimatized: Journal of 

Ichthyology, v. 14, no. 6, p. 842-847.

Nikolsky, G.V., 1963, The Ecology of Fishes: New York, 

Academic Press, 352 p.

Nikolsky, G.V., 1954, Special Ichthyology (Chastnaya 

ikhtiologiya) (2d ed.): Moscow, USSR Ministry of Culture, 

[Translated from Russian, 1961, for the National Science 

Foundation, Washington, D.C., and the Smithsonian Institution by the Israel Program for Scientific Translations, 

Jerusalem.]

References Cited 85
Nilsson, G.E., Rosén, Peter, and Johansson, Dan, 1993, 

Anoxic depression of spontaneous locomotor activity in 

Crucian carp quantified by a computerized imaging technique: Journal of Experimental Biology, v. 180, p. 153-162.

Nixon, D.E., and Miller, R.L., 1978, Movements of grass carp, 

Ctenopharyngodon idella, in an open reservoir system as 

determined by underwater telemetry: Transactions of the 

American Fisheries Society, v. 107, no. 1, p. 146-148.

O’Maoileidigh, N., and Bracken, J.J., 1989, Biology of the 

tench, Tinca tinca (L.), in an Irish lake: Aquaculture and 

Fisheries Management, v. 20, p. 199-209.

Opuszyński, K., Lirski, A., Myszkowski, L., and Wolnicki, 

J., 1989, Upper lethal and rearing temperature for juvenile 

common carp, Cyprinus carpio L., and silver carp, Hypophthalmichthys molitrix (Valenciennes): Aquaculture and 

Fisheries Management, v. 20, p. 287-294.

Opuszyński, K., and Shireman, J.V., 1993, Food habits, feeding behaviour and impact of triploid bighead carp, Hypophthyalmichthys nobilis, in experimental ponds: Journal of 

Fish Biology, v. 42, p. 517-530.

Opuszyński, Karol, and Shireman, J.V., 1995, Herbivorous 

fishes: Culture and use for weed management: CRC Press. 

Page, L.M., and Burr, B.M., 1991, A field guide to fresh­water 

fishes of North America north of Mexico: New York, 

Houghton Mifflin Company.

Panek, F.M., 1987, Biology and ecology of carp, in Cooper 

E.L., ed., Carp in North America: Bethesda, Md., American 

Fisheries Society, p. 1-15.

Pearl River Fisheries Research Institute (PRFRI), 1991, The 

freshwater fishes of Guangdong Province: Chinese Academy of Fisheries Science, Guangdong Science and Technology Press.

Penttinen, Olli-Pekka, and Holopainen, I.J., 1992, Seasonal 

feeding activity and ontogenetic dietary shifts in Crucian 

carp, Carassius carassius: Environmental Biology of 

Fishes, v. 33, nos. 1-2, p. 215-221.

Pénzes, Bethen, and Tölg, István, 1983, Goldfish and ornamental carp: Woodbury, N.Y., Barron’s, 127 p.

Perea, P.J., 2002, Asian carp invasion: Fish farm escapees 

threaten native river fish communities and boaters as well: 

Illinois Periodicals Online, Northern Illinois University 

Libraries, URL: http://www.lib.niu.edu/ipo/oi020508.html.

Perez-Bote, J.L., Blasco, M., Da Silva, J.L., and Ruiz de 

la Concha, J.I., 1998, The diet of tench, Tinca tinca, in

Ruiz, M.B., ed., La Tencha, un Recurso Irrenunciable para 

Extremadura., Camara Oficial de Comercio e Industria de 

Caceres, p. 111-115. [In Spanish with English summary.]

Perrow, M.R., Jowitt, A.J.D., and Johnson, S.R., 1996, Factors 

affecting the habitat selection of tench in a shallow eutrophic lake: Journal of Fish Biology, v. 48, p. 859-870.

Pflieger, W.L., 1975, The fishes of Missouri: Missouri Department of Conservation, 343 p.

Piironen, Jorma, and Holopainen, I.J., 1986, A note on 

seasonality in anoxia tolerance of Crucian carp (Carassius 

carassius [L.]) in the laboratory: Annales Zoologici Fennici, 

v. 23, p. 335-338.

Pimpicka, Elżbieta, 1991, Fecundity of tench (Tinca tinca L.) 

females in Lake Drwęckie: Acta Ichthyologica et Piscatoria, 

v. 21, no. 2, p. 129-141.

Pitt, T.K., Garside, E.T., and Hepburn, R.L., 1956, Temperature selection of the carp (Cyprinus carpio Linn.): Canadian 

Journal of Zoology, v. 34, p. 555-557.

Prejs, Andrzej, 1973, Experimentally increased fish stock in 

the pond type Lake Warniak. IV: Feeding of introduced and 

autochthonous non-predatory fish: Ekologia Polska, v. 21, 

no. 30, p. 465-504.

Prokeš, Miroslav, and Baruš, Vlastimil, 1996, On the natural 

hybrid between common carp (Cyprinus carpio) and Prussian carp (Carassius auratus gibelio) in the Czech Republic: 

Folia Zoologica, v. 45, no. 3, p. 277-282.

Przybylski, M., 1996, The diel feeding pattern of bitterling, 

Rhodeus sericeus amarus (Bloch) in the Wieprz-Krzna 

Canal, Poland: Polskie Archiwum Hydrobiologii, v. 43, 

no. 2, p. 203-222. 

Przybylski, M., and Zieba, G., 2000, Microhabitat preference 

of European bitterling, Rhodeus sericeus in the Drzeqiczka 

River (Pilica Basin): Polskie Archiwum Hydrobiologii, 

v. 47, no. 1, p. 99-114. 

Rai, Ash Kumar, 2000, Evaluation of natural food for planktivorous fish in Lakes Phewa, Begnas, and Rupa in Pokhara 

Valley, Nepal: Limnology, v. 1, p. 81-89.

Raicu, P., Taisescu, E., and Bănărescu, P., 1981, Carassius 

carassius and C. auratus, a pair of diploid and tetraploid 

representative species (Pisces, Cyprinidae): Cytologia, 

v. 46, p. 233-240.

Reichard, Martin, and Jurajda, Pavel, 1999, Patterns of ontogenetic changes in relative growth in the precocial cyprinid, 

bitterling (Rhodeus sericeus): Netherlands Journal of Zoology, v. 49, no. 2, p. 111-124.

Reichard, Martin, Jurajda, Pavel, and Ondračková, M., 2002, 

Interannual variability in seasonal dynamics and species 

composition of drifting young-of-the-year fishes in two 

European lowland rivers: Journal of Fish Biology, v. 60, 

no. 1, p. 87-101. 

Reichard, Martin, Jurajda, Pavel, and Smith, Carl, 2004, Malemale interference competition decreases spawning rate in 

the European bitterling (Rhodeus sericeus): Behavioral 

Ecology and Sociobiology, v. 56, p. 34-41.

Reynolds, J.D., and Guillaume, H.P., 1998, Effects of phosphate on the reproductive symbiosis between bitterling and 

freshwater mussels: Implications for conservation: Journal 

of Applied Ecology, v. 35, no. 4, p. 575-581.

86  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Rheinberger, Veronika, Hofer, Rudolf, and Wieser, Wolfgang, 

1987, Growth and habitat separation in eight cohorts of 

three species of cyprinids in a subalpine lake: Environmental Biology of Fishes, v. 18, no. 3, p. 209-217.

Richardson, M.J., Whoriskey, F.G., and Roy, L.H., 1995, 

Turbidity generation and biological impacts of an exotic 

fish Carassius auratus, introduced into shallow seasonally 

anoxic ponds: Journal of Fish Biology, v. 47, p. 579-585.

Roberts, Tyson, 1986, A new species and genus of fish from 

Burma, one of the smallest living vertebrates: Environmental Biology of Fishes, v. 16, p. 231-241.

Robison, H.W., and Buchanan, T.M., 1988, Fishes of Arkansas: Fayetteville, Ark., University of Arkansas Press, 536 p.

Rosa, H., Jr., 1958, A synopsis of biological data on tench, 

Tinca tinca: Food and Agriculture Organization, Fisheries 

Division, FAO/58/2/951, 24 p., 2 pls.

Ross, S.T., 2001, Inland fishes of Mississippi: University Press 

of Mississippi, 624 p.

Ryabov, I. N., 1979, Intersubfamily hybridization of the family 

Cyprinidae: Journal of Ichthyology, v. 19, no. 6, p. 57-73.

Sanchez-Herrera, C.F., Gallardo, J.M., Ceballos, E.G., Perez, 

J.M.O., and Dominguez, J.G., 1998, Utilization of artificial spawning substrate in the reproduction of tench Tinca 

tinca (L.): Polish Archives of Hydrobiology, v. 45, no. 3, 

p. 435-438.

Schindler, Otto, 1957, Freshwater fishes: London, Thames and 

Hudson. 

Schmidt, R.E., and McGurk, J., 1982, Biology of the European bitterling Rhodeus sericeus (Pisces: Cyprinidae) in the 

Bronx River, New York, USA: An apparently benign exotic 

species: Biological Conservation, v. 24, p. 157-162.

Schmidt, R.E., Samaritan, J.M., and Pappantoniou, Antonias, 

1981, Status of the Bitterling, Rhodeus sericeus, in southeastern New York: Copeia, no. 2, p. 481-482.

Schrank, S.J., Braaten, P.J., and Guy, C.S., 2001, Spatiotemporal variation in density of larval bighead carp in the Lower 

Missouri River: Transactions of the American Fisheries 

Society, v. 130, p. 809-814.

Schwartz, F.J., 1964, Natural salinity tolerances of some freshwater fishes: Underwater Naturalist, v. 2, no. 2, p. 13-15.

Schwartz, F.J., 1972, World literature to fish hybrids with an 

analysis by family, species, and hybrid: Publications of the 

Gulf Coast Research Laboratory Museum, no. 3. 328 p.

Schwartz, F.J., 1981, World literature to fish hybrids with 

an analysis by family, species, and hybrid: Supplement 1: 

Seattle, Wash., National Oceanic and Atmospheric Administration (NOAA), Technical Report NMFS SSRF-750. 507 p.

Scott, W.B., and Crossman, E.J., 1973, Freshwater fishes 

of Canada: Ottawa, Fisheries Research Board of Canada, 

Bulletin 184, 966 p.

Seeley, H.G., 1886, The freshwater fishes of Europe: London, 

Cassell and Company, 444 p.

Shapolvalov, Leo, 1944, The tench in California: California 

Fish and Game, v. 30, no. 1, p. 54-57.

Shireman, J.V., and Smith, C.R., 1983, Synopsis of biological data on the grass carp, Ctenopharyngodon idella 

(Cuvier and Valenciennes, 1844): FAO Fish Synopsis 135, 

FIR/S135, 86 p.

Singh, S.B., Dey, R.K., and Reddy, P.V.G.K., 1976, Some 

additional notes on the piscivorous habits of the grass carps 

(Ctenopharyngodon idella): Aquaculture, v. 9, p. 195-198.

Smith, Carl, Reichard, Martin, Jurajda, Pavel, and Przybylski, 

Miroslaw, 2004, The reproductive ecology of the European 

bitterling (Rhodeus sericeus): Journal of the Zoological 

Society of London, v. 262, p. 107-124.

Smith, Carl, Rippon, Karina, Douglas, Alexa, and Jurajda, 

Pavel, 2001, A proximate cue for oviposition site choice in 

the bitterling (Rhodeus sericeus): Freshwater Biology, v. 46, 

no. 7, p. 903-911.

Smith, C.L., 1985, The inland fishes of New York State: 

Albany, New York State Department of Environmental 

Conservation, 522 p.

Smith, H.M., 1945, The fresh-water fishes of Siam or 

Thailand: U.S Natural Museum, Bulletin 188, 622 p.

Smith, P.W., 1979, The fishes of Illinois: Urbana, University 

of Illinois Press, 314 p.

Snyder, D.E., Mulhall Snyder, M.B., Douglas, S.C., 1977, 

Identification of golden shiner, Notemigonus crysoleucas, 

spotfin shiner, Notropis spilopterus, and fathead minnow, 

Pimephales promelas, larvae: Journal of the Fisheries 

Research Board of Canada, v. 34, no. 9, p.1397-1409.

Soin, S.G., and Sukhanova, A.I., 1972, Comparative morphological analysis of the development of the grass carp, the 

black carp, the silver carp and the bighead (Cyprinidae): 

Journal of Ichthyology, v. 12, no. 1, p. 61-71.

Spotila, J.R., Terpin, K.M., Koons, R.R., and Bonati, R.L., 

1979, Temperature requirements of fishes from eastern Lake 

Erie and upper Niagara River: Environmental Biology of 

Fishes, v. 4, no. 3, p. 281-307.

Stanley, J.G., and Jones, J.B., 1976, Morphology of androgenetic and gynogenetic grass carp, Ctenopharyngodon idella 

(Valenciennes): Journal of Fish Biology, v. 9, p. 523-528.

Stanley, J.G., Miley, W.W., II, Sutton, D.L., 1978, Reproductive requirements and likelihood for naturalization of 

escaped grass carp in the United States: Transactions of the 

American Fisheries Society, v. 107, no. 1, p. 119-128.

Starling, Fernando, L.R.M., 1993, Control of eutrophication 

by silver carp (Hypophthalmichthys molitrix) in the tropical 

Paranoá Reservoir (Brasília, Brazil): A mesocosm experiment: Hydrobiologia, v. 257, p. 143-152.

References Cited 87
Sterba, Günther, 1973, Freshwater fishes of the world: 

Neptune City, N.J., T.F.H. Publications.

Stevenson, J.H., 1965, Observations on grass carp in 

Arkansas: Progressive Fish-Culturist, v. 27, p. 203-206

Strauss, R.E., and Bond, C.E., 1990, Taxonomic methods: 

Morphology, in Schreck, C.G., and Moyle, P.B., eds., 

Methods for fish biology: Bethesda, Md., American 

Fisheries Society, p. 109-140.

Sublette, J.E., Hatch, M.D., and Sublette, Mary, 1990, The 

fishes of New Mexico: Albuquerque, University of New 

Mexico Press, 393 p.

Summerfelt, R.C., Mauck, P.E., and Mensinger, Gary, 1971, 

Food habits of the carp, Cyprinus carpio L. in five Oklahoma reservoirs: Proceedings of the Southeastern Association of Game and Fish Commissions, v. 24, p. 352-377.

Svärdson, Gunnar, 1949, Note on spawning habits of Leucisus 

erythrophthalmus (L.), Abramis brama (L.), and Esox lucius

(L.): Institute of Freshwater Research, Sweden, Drottningholm, Report no. 29, p.102-107.

Swift, Camm, Yeager, R.W., and Parrish, P.R., 1977, Distribution and natural history of the fresh and brackish water 

fishes of the Ochlocknee River, Florida and Georgia: Tallahassee, Fla., Tall Timbers Research Station, Bulletin no. 20, 

111 p.

Szczerbowski, J.A., 2001, Carassius auratus (Linnaeus, 

1758), in Bănărescu, P.M., and Paepke, H.J., eds., The 

freshwater fishes of Europe, v. 5/III; Cyprinidae 2/III 

and Gasterosteidae: AULA-Verlag GmbH Wiebelsheim, 

Germany, p. 5-41.

Szczerbowski, J.A., and Szczerbowski, A.J., 2001, Carassius carassius (Linnaeus, 1758), in Bănărescu, P.M., and 

Paepke, H.J., eds., The freshwater fishes of Europe, v. 5/III; 

Cyprinidae 2/III and Gasterosteidae: AULA-Verlag GmbH 

Wiebelsheim, Germany, p. 43-78.

Tang, Yun-An, 1960a, Report of the investigation on spawning of Chinese carps in Ah Kung Tian Reservoir: Tainan, 

Taiwan: Taiwan Fisheries Research Institute, Taiwan Fish 

Culture Station, 11 p.

Tang, Yun-An, 1960b, Reproduction of the Chinese carps, 

Ctenopharyngodon idellus and Hypophthalmichthys molitrix in a reservoir in Taiwan: Japanese Journal of Icthythology, v. 8, nos. 1-2, p.1-2.

Tang, Yun-An, 1965, Progress in the hormone spawning of 

pondfishes in Taiwan: Proceedings of the Indo-Pacific Fisheries Council, v. 11, no. 2, p. 122-127.

Tave, Douglas, 1988, Genetics of scale pattern in common 

carp: Aquaculture Magazine, November/December, 

p. 59-61.

Taylor, Jane, and Mahon, Robin, 1977, Hybridization of 

Cyprinus carpio and Carassius auratus, the first two exotic 

species in the lower Laurentian Great Lakes: Environmental 

Biology of Fishes, v. 1, no. 2, p. 205-208.

Terrell, J.W., and Fox, A.C., 1974, Food habits, growth, and 

catchability of grass carp in the absence of aquatic vegetation, in Rogers, W.A., ed., Proceedings of the 28th Annual 

Conference of the Southeastern Association of Game and 

Fish Commissioners, p. 251-259.

Trautman, M.B., 1981, The fishes of Ohio: Columbus, Ohio 

State University Press, 782 p.

Verigin, B.V., and Makeeva, A.P., 1974, Hybridization of the 

carp and bighead: Soviet Genetics, v. 8, no. 7, p. 844-851.

Verigin, B.V., Makeeva, A.P., and Shubnikova, N.G., 1975, 

The morphology of underyearling hybrids of the bighead 

Aristichthys nobilis and the grass carp Ctenopharyngodon 

idella: Journal of Ichthyology, v. 15, no. 2, p. 226-231.

Verigin, B.V., Makeeva, A.P., and Shubnikova, N.G., 1979, 

A case of natural hybridization between Hypophthalmichthys molitrix and Aristichthys nobilis (Pisces, Cyprinidae): Zoolosicheskifi Zhurnal, v. 58, no. 2, p. 190-196. 

[In Russian with English summary.]

Verigin, B.V., Shakha, D.N., and Kamilov, B.G., 1990, Correlation among reproductive indicators of the silver carp, 

Hypophthalmichthys molitrix, and the bighead, Aristichthys 

nobilis: Journal of Ichthyology, v. 30, p. 80-92.

Victorovsky, R.M., 1966, (Morphological characteristic of 

carp [Cyprinus carpio L.] X tench [Tinca tinca L.] hybrids): 

Izv. Gos. Nauchno-Issled. Inst. Ozern. Rechn. Rybn. Khoz., 

v. 66, p. 136-142. [In Russian with English summary.]

Vinogradov, V.K., Erokhina, L.V., Savin, G.I., and Konradt, 

A.G., 1966, Methods of artificial breeding of herbivorous 

fishes: Biological Abstracts, v. 48, no. 20. [Abstract 99805, 

1967.]

von Oertzen, Jörg-A., 1985, Resistance and capacity adaptation of juvenile silver carp, Hypophthalmichthys molitrix 

(Val.), to temperature and salinity: Aquaculture, v. 44, no. 4, 

p. 321-333.

Voropaev, N.V., 1968, Morphological characteristics, diet and 

certain fish farming attributes of silver carp and bighead 

and their hybrids: Aquatic Weeds Abstracts, v. 20, no. 2. 

[Abstract no. 744, 1970.]

Vovk, P.S., 1979, Temperature and food adaptation of the Far 

East herbivorous fishes: Pacific Science Congress Proceedings, p. 41-42.

Walker, R.M., and Johansen, P.H., 1977, Anaerobic metabolism in goldfish, Carassius auratus: Canadian Journal of 

Zoology, v. 55, no. 8, p. 1304-1311.

Wallen, I.E., 1951, The direct effect of turbidity on fishes: 

Oklahoma Agricultural and Mechanical College, Bulletin, 

v. 48, no. 2., p. 1-27.

Waller, U., 1985, Study on the physiological responses of the 

silver carp Hypophthalmichthys molitrix under the specific 

conditions in Schlewsig-Holstein with special regard to 

its brackish water tolerance, in Experiences and problems 

88  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
in introducing nonindigneous species: Hamburg, Arbeiten 

des Deutschen Fischerei-Verbandes, no. 37a., p. 105-128. 

[In German with English summary.]

Wang, Ji-Qiao, Huanliang Lui, Hongyu Po, and Lina Fan, 

1997, Influence of salinity on food consumption, growth 

and energy conversion efficiency of common carp (Cyprinus carpio) fingerlings: Aquaculture, v. 148, p. 115-124.

Ware, F.J., and Gasaway, R.D., 1978, Effects of grass carp on 

native fish populations in two Florida lakes: Proceedings of 

the 30th Annual Conference of the Southeastern Association 

of Fish and Wildlife Agencies, p. 324-335.

Watkins, C.E., Shireman, J.V., Rottman, R.W., and Collee, 

D.E., 1981, Food habits of fingerling grass carp: The 

Progressive Fish-Culturist, v. 43, no. 2, p. 95-97.

Wattendorf, R.J., 1986, Rapid identification of triploid grass 

carp with a Coulter counter and channelyzer: Progressive 

Fish-Culturist, v. 48, no. 2, p. 125-132.

Welcomme, R.L., 1988, International introductions of inland 

aquatic species: Food and Agriculture Organization of the 

United Nations (FAO), Rome, Italy, FAO Fisheries Technical Paper 294, 318 p.

Wheeler, Alwyne, 1969, The fishes of the British Isles and 

north-west Europe: East Lansing, Michigan State University 

Press, 613 p.

Wheeler, Alwyne, 1978. Key to the fishes of northern Europe: 

London, Frederick Warne Ltd.

Whitworth, W.R., 1996, Freshwater fishes of Connecticut 

(2d ed.): State Geological and Natural History Survey of 

Connecticut, Bulletin 114, 243 p.

Wieser, W., 1991, Physiological energetics and ecophysiology, in Winfield, I.J., and Nelson, J.S., eds., Cyprinid fishes: 

Systematics, biology and exploitation: London, Chapman 

and Hall, p. 426-455.

Woźniewski, Michał, and Opuszyński, Karol, 1988, Threshold 

oxygen content in water for juvenile stages of the cyprinids 

(Ctenopharyngodon idella Val., Hypophthalmichthys molitrix Val., Aristichthys nobilis Rich., Cyprinus carpio L.): 

Roczniki Nauk Rolniczych, v. 101, no. 4, p. 51-59. 

[In Polish with English summary.]

Wu, Hsien-Wen, and others 1964a, Chinese fishes of the 

family Cyprinidae, Vol. 1: Shanghai, China, Shanghai 

Publishing House of Science and Technology. [In Chinese.]

Wu, Xian-Wen, Gan-Rong Yang, Pei-Qi Yue, and Hong-Jin 

Huang, eds., 1964b, The economic animals of China: Freshwater fishes: Beijing, China, Science Press, [In Chinese.]

Wydoski, R.S., and Whitney, R.R., 2003, Inland fishes of 

Washington: Bethesda, Md., American Fisheries Society 

and the University of Washington Press. 

Xie Ping, 2003, Silver carp and bighead, and their use in the 

control of algal blooms: Beijing, Science Press, 134 p.

Yamamoto, M.N., and Tagawa, A.W., 2000, Hawaii’s native 

and exotic freshwater animals: Honolulu, Mutual Publishing, 200 p.

Yen, Mai Dinh, 1985, Species composition and distribution of 

the freshwater fish fauna of the North of Vietnam: Hydrobiologia, v. 121, p. 281-286.

Yih, Peh-Lu, and Tze-Sin Liang, 1964, Natural conditions of 

the spawning grounds of the “domestic fishes” in Yangtze River and essential external factor for spawning: Acta 

Hydrobiologica Sinica , v. 5, no. 1, p.1-15. [In Chinese with 

English summary.]

Yilmaz, F., 2002, Reproductive biology of the tench Tinca 

tinca (L., 1758) inhabiting Porsuk Dame Lake (Kutahya, 

Turkey): Fisheries Research, v. 55, no. 1-3, p. 313-317.

Yue, Peiqi, and others, 2000, Fauna sinica; Osteichthyes; 

Cypriniformes III: Beijing, China, Science Press, 661 p.

Zang, Weiling, Wu Wang, Ling Ye, Zheng Yu, Guofan Ni, and 

Bin Zhao, 1989, Toxic effects of salinity (S ppt) on some 

freshwater fishes: Oceanologia et Limnologia Sinica, v. 20, 

no. 5, p. 445-452. [In Chinese with English summary.]

Zhadin, V.I., and Gerd, S.V., 1963, Fauna and flora of the 

rivers lakes and reservoirs of the U.S.S.R.: Translated 

from Russian by the Israel Program for Scientific Translations, Jerusalem, 626 p. [Originally published in Moskow, 

1961, by Gosudarstvennoe Uchebno-Pedagogicheskoe 

Izdatel’stvo Misisterstva Prosveshcheniya RSFSR.]

Zhong, L., Chao, J., Zeng, M., Ouyang, H., Chen, F., Li, Y, 

Zhao, A., and Su, Z., 1980, Pond fish culture in China: 

Guangzhou, Pearl River Fisheries Research Institute, China 

National Bureau of Aquatic Products.

Zhou, Chunsheng, Zhixin Liang, and Heinan Huang, 1980, 

Ecological features of the spawning of certain fishes in the 

Hanjiang River after the construction of dams: Acta Hydrobiologica Sinica, v. 7, no. 2, p. 188-193. [In Chinese with 

English summary.]

Zhul’kov, A.I., and Nikiforov, S.N., 1988, Some morphological and biological data on the bitterling Rhodeus sericeus

from the Tym’ River (Sakhalin I.): Journal of Ichthyology, 

v. 28, no. 1, p. 149-153.

References Cited 89
One of the earliest U.S. records of Silver Carp from the wild, this fish was captured in the 

lower Mississippi River near Greenville, Mississippi, about 1990. (Photo by Leo G. Nico.)

90 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Appendixes
Goldfish, 2.2 kg, from Kalvemose 

Lake, Denmark. (Photo copyright 

© www.jjphoto.dk, courtesy of 

Johnny Jensen.)

92  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Appendix A. Foreign cyprinids established or reported from the United States.

Nonindigenous foreign cyprinids introduced to inland waters are listed by state. The matrix is largely based on 

Fuller and others (1999) although several records have been added or modified due to new information.

Key to symbols:

E - Established, one or more breeding populations known to exist.

E? - reported from state, possibly established, existence of a breeding population not confirmed.

X – Only known established population(s) eradicated or extirpated.

X? - previously known to be established, recent information indicates possible extirpation.

R - reported from one or more localities, no evidence of establishment.

R? - reported, but record or records not fully confirmed (that is, some doubt remains concerning identification). 

asterisk (*) – indicates that we have located (or found published reference to) voucher specimen(s) that support 

one or more of a state’s records. In most cases, the voucher has been deposited and catalogued in a recognized 

ichthyological collection; however, not all specimens have been examined to verify identification.

Note: For states where a species is listed as established, possibly established, or extirpated, other records may 

indicate that the species has been reported from one or more sites within the same state.

Appendix A 93
Appendix A. Foreign cyprinids established or reported from the United States.

Scientific Name Common Name

 Alabama

 Alaska

 Arizona

 Arkansas

 California

 Colorado

 Connecticut

 Delaware

 Florida

 Georgia

 Hawaii

 Idaho

 Illinois

 Indiana

 Iowa

 Kansas

 Kentucky

 Louisiana

 Maine

 Maryland

 Massachusetts

 Michigan

 Minnesota

 Mississippi

 Missouri

Brachydanio rerio Zebra Danio

R

R R*

Carassius auratus Goldfish E?* E* E?* E*

E

E

E R* E*

E

E E* E* E* E*

E E?

R E* E* E*

E E?* E*

Carassius carassius (?) Crucian Carp

X

Ctenopharyngodon idella Grass Carp

R

R

E

R

R

R

R R*

R

R

R E*

R E*

R

E E*

R

R R* E?

E

E

Cyprinus carpio Common Carp E* E* E* E* E*

E E* E* E*

E E* E* E* E* E* E* E* E? E* E* E* E* E* E*

Danio malabaricus Malabar Danio R*Hypophthalmichthys molitrix Silver Carp

R

R

E

R R* E*

E

E

R

E E*

E

E

Hypophthalmichthys nobilis Bighead Carp

R

R

E

R

R

R E*

E

E E*

E E*

R

E

E

Leuciscus idus Ide R?

X R? R? R? R? R? E? X? R? R? R?

Morulius chrysophekadion Black Sharkminnow

R

Mylopharyngodon piceus Black Carp R* E?* R?

R

Puntius conchonius Rosy Barb

R

Puntius filamentosus Blackspot Barb X?Puntius gelius Dwarf Barb

R

Puntius schwanenfeldii Tinfoil Barb

R

Puntius semifasciolatus Green Barb X?Puntius tetrazona Tiger Barb R*

R

Rhodeus sericeus BitterlingScardinius erythrophthalmus Rudd

R

R

R R? R* R? X?

E E*

R

Tinca tinca Tench R?

R R?

E E* X?

X R?

R E*

R

R

R

R R?

R E?* R?

R R*

Number of 

species by stateTotal 7 0 6 8 7 7 7 4 14 4 5 4 10 8 6 8 6 8 4 5 6 4 5 6 9 E/E? 2 0 2 5 3 3 2 2 1 2 2 3 5 4 5 3 5 6 3 3 3 2 3 5 5 R/R? 5 0 4 3 4 4 3 1 13 2 1 1 4 4 1 4 1 2 1 1 3 2 2 1 4 X/X? 0 0 0 0 0 0 2 1 0 0 2 0 1 0 0 1 0 0 0 1 0 0 0 0 0

94  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Appendix A. Foreign cyprinids established or reported from the United States. (Continued)

Common Name

 Montana

 Nebraska

 Nevada

 New Hampshire

 New Jersey

 New Mexico

 New York

 North Carolina

 North Dakota

 Ohio

 Oklahoma

 Oregon

 Pennsylvania

 Rhode Island

 South Carolina

 South Dakota

 Tennessee

 Texas

 Utah

 Vermont

 Virginia

 Virginia

 Washington

 West Virginia

 Wisconsin

 Wyoming

 E/E?

 R/R?

 X/X?

Totals

Zebra Danio X 0 3 1 4Goldfish E E* E* E* E?* E? E* E?* E? E* E E? E* E* E* E E* E* R R E* E* E E?* E E 45 4 0 49Crucian Carp R? 0 1 1 2Grass Carp E? R R R R R* R R R R R R R R E E R R R R R R R 11 34 0 45Common Carp E E* E* E* E* E* E* E* E* E* E* E* E* E E* E* E* E* E* E E* E* E* E* E* E* 49 0 0 49Malabar Danio R 0 2 0 2Silver Carp R R E 9 7 0 16Bighead Carp E R R R E R R R 11 12 0 23Ide R R? X* R? R? X R R X X R? 1 16 5 22Black Sharkminnow 0 1 0 1Black Carp 1 3 0 4Rosy Barb 0 1 0 1Blackspot Barb 0 0 1 1Dwarf Barb 0 1 0 1Tinfoil Barb 0 1 0 1Green Barb 0 0 1 1Tiger Barb R R 0 4 0 4Bitterling X?* 0 0 1 1Rudd E X E* R E? E E? R* E*? E*? R R X 8 11 3 22Tench R R R X* X? R R R X* R R R R R R? X* X* E* R? R 5 28 6 39

Number of 

species by stateTotal 2 8 5 3 6 5 7 5 3 6 6 4 6 2 4 6 7 9 4 4 6 6 5 7 6 4 E/E? 2 5 2 2 2 2 3 2 2 2 2 2 3 2 2 3 5 4 1 1 3 3 3 2 2 2 R/R? 0 3 3 1 3 1 1 3 1 4 4 1 2 0 2 3 2 5 3 3 1 1 2 5 3 2 X/X? 0 0 0 0 1 2 3 0 0 0 0 1 1 0 0 0 0 0 0 0 2 2 0 0 1 0

Appendix A 95
Grass Carp, Caloosahatchee River, 

Florida, December 19, 1997. (Photo 

by Leo G. Nico.)

96  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Appendix B  97

Appendix B. Meristics of foreign nonindigenous cyprinids and selected hybrids.

This appendix contains meristic characters for the eleven foreign nonindigenous cyprinids treated in this guide, as 

well as some of their hybrids. Each table presents meristic information from a number of reports, generally ranging over a 

wide geographic area (often including data from populations in both native and non-native areas). Because the soft rays of 

the dorsal and anal fins are often difficult to discern, many authors typically report only a single number, which includes 

one unbranched ray plus all branched rays. We have reproduced these counts as given by the original authors. In contrast, 

some authors give counts for both unbranched and branched rays in the fins. The format of these counts has been standardized by using Roman numerals to indicate unbranched rays followed by Arabic numerals (in parentheses) to represent the 

number of soft branched rays. Gill-raker counts are based on the first (outer) gill arch. All gill rakers are counted, including 

small rudimentary ones. Some authors give either upper and lower limb counts, or inner and outer (anterior and posterior) 

counts, and we have reported those data where available. For more information on reporting meristics, see “Methods.”

Goldfish (Carassius auratus)

Citation

Nikolyukin 

1946, 

in Berg 

(1964)

Berg 

(1964)

Kiselov 

(1962), in

Szczerbowski (2001)

Taylor and 

Mahon 

(1977)

Radimowski 

(1973), in

Szczerbowski (2001)

Radimowski 

(1973), in

Szczerbowski (2001)

Bănărescu 

(1964)

Scott 

and 

Crossman 

(1973)

Yue and

others

(2000)

Nakamura 

(1969)

Wheeler 

(1969)

Source locale Russia Russia Ukraine Laurentian 

Great Lakes China Ukraine Romania Canada China Japan NW Europe

Lateral-line 

scales 28-31 28-33 26-31 28-31 28-30 26-31 28-32 27-30 27-30 30-33 28-33

Dorsal rays iii-iv 

(15-18)

iii-iv 

 (14-19)

iii-iv 

 (13-19)

ii-iii 

(15-18)

iii 

(16-18)

iii 

(15-19)

iii-iv

(14-18) (15-18) iii (15-19)

iii 

(16-18)

iii-iv 

(15-19)

Anal rays iii (5-6) ii-iii 

(5-6)

ii-iii 

(5-6)

iii 

(5-6)

iii 

(5-6)

iii 

(5) (5-6) iii (5)

iii 

(5)

ii-iii 

(5-6)

Pectoral rays i (13-15) i (14-18) (15-17) i (16-17)

Pelvic rays i (7-9) i (7-8) (8-9) i (8)

Vertebrae 29-31 29-31 29-31 26-31 25-31 29-31 28-29 28-30

Gill rakers 40-48 39-50 38-47

39-47 

outside, 

47-53 inside

37-46 38-45 40-52 37-43

Crucian Carp (Carassius carassius)

Citation

Drjagin (1949, in

Szczerbowski 

and Szczerbowski 

(2001)

Szczerbowski 

(1995), 

in Szczerbowski 

and Szczerbowski 

(2001)

Nikolyukin 

(1946), in Berg 

(1964)

Bănărescu 

(1964)

Yue and

others

 (2000)

Nikolyukin 

(1946), in

Berg (1964)

Wheeler (1969)

Source locale Russia Poland Russia Romania China Russia NW Europe

Lateral-line scales 28-37 32-35 32-35 30-35 32-34 29-36 32-35

Dorsal rays iii-iv (14-21) iii-iv (16-19) iii-iv (16-19) iii-iv (14-17) iii (16-18) iii-iv (16-20) iii-iv (14-21)

Anal rays ii-iii (6-8) ii-iii (5-8) iii (5-6) iii (5-7) iii (6-7) iii (6-7) iii (6-8)

Pectoral rays i (14-16)

Pelvic rays i (8)

Vertebrae 31-33 30-33 31-34 32-33

Gill rakers 22-33 22-28 28-33 23-33 26-30 26-31
Common Carp (Cyprinus carpio)

Citation Berg (1964) Taylor and 

Mahon (1977)

Kirpichnikov 

(1967), in Baruš 

and others 

(2001)

Bănărescu 

(1964)

Balon 

(1974, 1995)

Scott and 

Crossman 

(1973)

Yue and

others

(2000)

Nakamura 

(1969)

Wheeler 

1969

Source locale Russia Laurentian 

Great Lakes China Romania Danube River Canada China Japan NW Europe

Lateral-line scales 32-40 37-40 33-39 34-40 34-40 35-39 32-40 33-36 35-40

Dorsal rays iii-iv (15-21) iii (18-20) (18-21) ii-iv (17-22) ii-iv

(18-22) (18-20) iv (16-22) iii (19-21) iii-iv (17-22)

Anal rays iii (5-6) ii-iii (5) ii-iii (4-6) ii-iii (4-5) (5) iii (5) iii (5) ii-iii (5)

Pectoral rays i (13-15) i (14-19) i (14-19) (14-17) i (14-16)

Pelvic rays i (7-8) ii (7-9) ii (7-9) (8-9) ii (8)

Vertebrae 36-38 35-36 31-32

Gill rakers 21-29 21-29 outside, 

27-31 inside 18-21 22-28

22-28 

inside; 29-

36 outside

Common Carp X Goldfish (Cyprinus carpio X Carassius auratus)

Citation Bănărescu 

(1964)

Taylor and Mahon 

(1977)

Prokeš and Baruš 

(1996)

Source locale Romania Laurentian Great Lakes Czech Republic

Lateral-line scales 38-39 32-35 36

Dorsal rays iii (21) iii-iv (17-18) iv (17)

Anal rays iii (6) ii-iii (5) iii (5)

Pectoral rays i (13-15) i (15)

Pelvic rays ii (8-9) I (7-8) ii (8)

Vertebrae 35 35

Pharyngeal teeth 1,1,3-3,1,1 0-1 on first and second 

row, 4 on third row 1,1,3-3,1,1

Gill rakers 24 30-40 outside, 

25-42 inside 25 outside, 31 inside

Common Carp X Crucian Carp (Cyprinus carpio X Carassius carassius)

Citation Nikolyukin (1937),

in Berg (1964)

Nikolyukin (1946),

in Berg (1964)

Jones and Linfield 

(1972)

Bănărescu 

(1964)

Source locale Russia Russia Britain Romania

Lateral-line scales 35-38 36-39 35-39

Dorsal rays iii-v (16-21) iii-iv (17-21) (19) iv (17-21)

Anal rays vvv (5-6) iii (5-6) (6) iii (4-5)

Vertebrae 33-36 33-37

Pectoral rays (15)

Pelvic rays (8)

Caudal rays (21)

Pharyngeal teeth Most often 

1,4-4,1

Most often 

1,4-4,1 1,4-4,1 Various, see text

Gill rakers 26-32

Barbels One on each side

98  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Grass Carp (Ctenopharyngodon idella)

Citation Berry and Low 

(1970) Berg (1964) Nakamura (1969) Chen (1998) Kilambi and Zdinak (1981)

Source locale Malaysia Russia Japan China Arkansas, USA

Lateral-line scales 40-42 43-45 37-39 38-44 38-45

Dorsal rays i-ii (8) iii (7) iii (7) iii (7)

Anal rays ii (8-9) iii (8) iii (8) iii (8-9) 8-10

Pectoral rays i (14-16) i (16-18) 15-18

Pelvic rays i (7-8) ii (8)

Vertebrae 41

Gill rakers 12 8-12 (lower limb, 

first arch)

Grass Carp X Bighead Carp (Ctenopharyngodon idella X Hypophthalmichthys nobilis)

Citation Berry and Low 

(1970)

Andriasheva 

(1968)

Cassani and 

others, (1984)

Verigin and others 

(1975)

Kilambi and 

Zdinak (1981)

Source locale Malaysia Russia Arkansas Arkansas

Lateral-line scales 52-65 60-67 42-59 42-57

Dorsal rays ii (8) i (6-8) (7)

Anal rays ii (10-11) 0-i (8-11) (8-10)

Pectoral rays i-ii (17-19) i (16-20) 17-21

Pelvic rays i-ii (7-8) i (7-8)

Gill rakers 18-23 

(lower limb, first arch)

Keel present present Sometimes present

Pharyngeal teeth 0,4-5,0 variable 

(see citation) 1,4-5,1

Black Carp (Mylopharyngodon piceus)

Citation Kimura(1934) Berg (1964) Nikolsky 

(1956)

Nakamura 

(1963, 1969)

Wu and 

others (1964a) Chu (1984) Chu and others (1989) Chen (1998)

Source locale China Russia Russia Japan? China China China China

Lateral-line scales 43 39-43 42-43 41-44 39-45 39-46 40-44 39-44

Dorsal rays iii (7) iii (7-8) iii (7) 8-9 or

iii (7-8) iii (7-8) iii (7) iii (7) iii (7)

Anal rays iii (8) iii (8) iii (8) 8-9 or

 iii(7-8) iii (8-9) iii (8) 8-9 iii (8-9)

Pectoral rays i (16) i (16) i (16) i (16-18)

Pelvic rays i (8) i (8) ii (8) i (8) ii (8)

Vertebrae 38-41 38-41 38

(n=1) 37-40

Gill rakers 4+14 19-21 19-21 14-18 15-21

usually 18-20 15-16 18-20

Appendix B  99
Bighead Carp (Hypophthalmichthys nobilis)

Citation

Antalfi and Tolg, 

in Opuszynski 

and Shireman

 (1995)

Nakamura 

(1969)

Nakamura 

(1963) Chen (1998) Berry and Low (1970)

Source locale Poland? Japan Japan China Malaysia

Lateral-line scales 114-120 99-112 106 91-108 98-100

Dorsal rays iii (10) iii (7,10) 8-11 iii (7-8) ii (8)

Anal rays iii (15-17) iii (12-14) 13-14 iii (10-13) ii (12-14)

Pectoral rays i (16-19) iI (17019)

Pelvic rays i (7-8) i (8-9)

Gill akers 130

Vertebrae 38

Silver Carp (Hypophthalmichthys molitrix)

Citation Berg (1964) Chen (1998) PRFRI (1991) Nakamura 

(1969)

Source locale Russia China China Japan

Lateral-line scales 110-124 91-120 108-120 98-116

Dorsal rays ii (7) iii (7) iii (7) iii (7)

Anal rays ii-iii (12-14) iii (11-13) iii (13) iii 12-14)

Pectoral rays i (16-17) i (17)

Pelvic rays i (7) i (7-8) i (8)

Vertebrae 37 37 37

Gill rakers about110

Ide (Leuciscus idus)

Citation Chen (1998) Bănărescu (1964) Berg (1964) Wheeler (1969)

Source locale China Romania Russia Western Europe

Lateral-line scales 55-59 55-61 55-63 56-61

Dorsal rays iii (8) iii (7-9) iii (8) iii (8)

Anal rays iii (9-11) iii (9-11) iii (9-12) iii (9-10)

Pectoral rays i (16-17)

Pelvic rays ii (8)

Vertebrae 44-47 44-45

Gill rakers 10-11 10-14

100 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Bitterling (Rhodeus sericeus)

Citation Wheeler (1969) Bănărescu (1964) Holčík and Jedlička 

(1994)

Holčík and Jedlička 

(1994)

Source locale NW Europe Romania Europe Amur Basin

Lateral-line scales 5-6 pored; 34-38 total 

scales on side

4-7 pored; 35-38 total 

scales on side

4-10 pored; 33-44 total 

scales on the side

0-9 pored, 32-45 total 

scales on the side

Dorsal rays iii (9-10) iii (8-10) ii-iii (8-11) ii-iv (7-11)

Anal rays iii (8-9) iii (8-10) ii-iii (8-11) ii-iv (6-11)

Pharyngeal teeth 0,5-5,0 0,5-5,0

Gill rakers 9-16 (outside) 9-13 (outside)

Rudd (Scardinius erythrophthalmus)

Citation Burkhead and Williams 

(1991) Berg (1964) Bănărescu (1964)

Source locale Arkansas Russia Romania

Lateral-line scales 38-41 37-43 39-42

Dorsal rays 9-11 iii (8-10) iii (8-9)

Anal rays 11-14 iii (9-12) iii (10-12)

Pectoral rays 15-16

Pelvic rays 8-9

Vertebrae 37-40 38-39

Gill rakers 10-13 11-12 11-12

Tench (Tinca tinca)

Citation Scott and 

Crossman (1973) Berg (1964) Jevtić (1979) Coad (2005) Wheeler (1969)

Source locale Canada Russia Yugoslavia Iran (and other 

locations) NW Europe

Lateral-line scales 95-105 90-110 (males); 

87-115 (females) 70-120

Dorsal rays 9 iii-iv (8) ii-iv (6-9) iii (8)

Anal rays 7-8 iii (6-8) iii-iv (5-9) iii (6-8)

Pectoral rays 13-18

Vertebrae 38-39 38-41 35-44

Gill rakers 13 10-16

Appendix B 101
Grass Carp, Caloosahatchee River, 

Florida, January 16, 1995. 

(Photo by Leo G. Nico.)

102  Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.—A Guide to their Identification
Appendix C 103

United States Geological Survey

Florida Integrated Science Center

Nonindigenous Aquatic Species Program

7920 NW 71st Street

Gainesville, Florida 32653

Telephone (352) 378-8181 Fax (352) 378-4956

http://nas.er.usgs.gov

Nonindigenous Aquatic Species Reporting Form

Common Name ___________________________________________________________

Genus ___________________________ Species __________________________

Subspecies _______________________ Date Collected ____________________

State ________County __________________ Drainage ______________________

Location (please be as specific as possible; for example, road crossing, distance, and direction to nearest town): ____________

_________________________________________________________________________

_________________________________________________________________________

_______________________________________________________

Identified by _____________________________________________________________

Collected by _____________________________________________________________

Method of collection ______________________________________________________

Number collected ________ Age class ________________ Size ______________

 (Adult, Juvenile, young-of-year) (TL, SL, or FL)

Method of disposal ________________________________________________________

(released, discarded, preserved, mounted, deposited in museum)

Specimen storage _________________________________________________________

(museum or agency’s name and catalogue number)

Comments _______________________________________________________________

_________________________________________________________________________

_________________________________________________________________________
Begin

Brancheddorsal rays: >13

Barbels:Pharyngeal teeth:

present

1, 1, 3-3, 1, 1

Common Carp

( ) Cyprinus carpio

Lateral-linescales: >85

Barbels:Pharyngeal teeth:

absent

0,4-4,0

Dorsal fin:Caudal fin:Peritoneum:Gill rakers:

upper edge straight or slightly concave

deeply emarginate without spot at base

blackish

35-52

Goldfish ( ) Carassius auratusDorsal fin:Caudal fin:Peritoneum:Gill rakers:

upper edge convex

slightly emarginate with blackish spot

at base (fades with growth)

light

22-33

Crucian Carp ( ) Carassius carassius

Barbels:Keel:

present

absent

Tench ( ) Tinca tincaBarbels:Keel:

absent

present

Sides:Ventral keel:Gill rakers on first arch:

silvery, without blotches

extends almost to junction of gills

fused into sponge-like apparatus

Silver Carp ( ) Hypophthalmichthys molitrix

Sides:Ventral keel:Gill rakers on first arch:

with small, irregular dark blotches

extends to pelvic fin base

slender, comblike, not fused

Bighead Carp ( ) Hypophthalmichthys nobilis

Lateral line

scales: 55-63

Ide ( ) Leuciscus idus

Keel: presentRudd (

)

Scardinius

erythrophthalmus

Keel: absent

Body color:Pharyngeal teeth:Peritoneum:

olivaceous or silvery white,

fins dusky

with elongate,

parallel grooves on grinding surfaces

silvery with blackish

blotches

Grass Carp ( ) Ctenopharyngodon idellaBody color:

:

Peritoneum:

dark brown or blue-gray,

fins dark

massive, molar-like,

smooth (not serrated or grooved)

black

Pharyngeal teethBlack Carp ( ) Mylopharyngodon piceus

Brancheddorsal rays: <12

Lateral-linescales: <65

Lateral-linescales: <50

1

2

3

4

5

6

7

8

9

10 Pored lateral-line scales: <12

Bitterling ( ) Rhodeus sericeus

Pored lateral-line

scales: 35-45

Abbreviated diagnostic key to foreign nonindigenous cyprinids of the United States.Blue numbers refer to couplets in key.Note: Not all diagnostic characters are included in this flow chart; refer to key (p. 7-13) and text for additional details.