# Corydoras

Corydoras is a genus of freshwater catfish in the family Callichthyidae and subfamily Corydoradinae. The species usually have more restricted areas of endemism than other callichthyids, but the area of distribution of the entire genus almost equals the area of distribution of the family, except for Panama where Corydoras is not present. Corydoras species are distributed in South America where they can be found from the east of the Andes to the Atlantic coast, from Trinidad to the Río de la Plata drainage in northern Argentina.
Species assigned to Corydoras display a broad diversity of body shapes and coloration. Corydoras are small fish, ranging from 2.5 to 12 cm (1.0 to 4.7 in) in SL., and are protected from predators by their body armor and by their sharp, typically venomous spines.

## Taxonomy

The name Corydoras is derived from the Greek kory (helmet) and doras (skin). Corydoras is by far the largest genus of Neotropical fishes with more than 160 species. It is the sole genus in the tribe Corydoradini. C. difluviatilis is recognized as the basalmost species of Corydoradini, exhibiting several plesiomorphic features compared to the other species of Corydoras. The type species for this genus is Corydoras geoffroy. Several hundred species are not yet classified, but kept by aquarists. These species are given 'C-numbers', originally devised by Hans-Georg Evers for the German fishkeeping magazine DATZ in 1993. As of February 2014, 158 C-numbers had been assigned, of which 32 had been assigned appropriate scientific names.
The species C. barbatus, C. macropterus and C. prionotos have been reclassified into the genus Scleromystax. Brochis had been differentiated from Corydoras due to the higher number of dorsal fin rays; however, Brochis has recently been suggested to be a synonym of Corydoras. This is contested and has not been universally accepted. The sixray corydoras belongs in Aspidoras.

### Brochis

Brochis is a formerly recognized genus of catfish. Between one and three fish of the Callichthyidae in the Siluriformes order are referred to as Brochis, however following recent classification these three species have been grouped in the genus Corydoras. The genus is considered defunct by most scientific authorities, or as a junior synonym or subgenus of Corydoras. Consequently, it is an example of Obsolete taxa
Despite being considered defunct, there are several morphological differences that fish formerly classified in the genus Brochis have. These include a noticeably larger body, a more lyre-like tail and most decisively, the extended dorsal fins that have more rays than those of Corydoras Corydoras have 7–10 rays on their dorsal fins, while Brochis have 10–18. Brochis are very large for their family, as all three species can exceed 8 cm (3.1 in) in length. In the Brochis stable, Corydoras splendens is the largest. It is also the largest Corydoras attaining a maximum size of 9.9 centimetres and 40 grams.

## Ecology

Corydoras are generally found in smaller-sized streams, along the margins of larger rivers, in marshes, and in ponds. They are native to slow-moving and almost still (but seldom stagnant) streams and small rivers of South America, where the water is shallow and very murky. Most species are bottom-dwellers, foraging in sand, gravel or detritus. The banks and sides of the streams are covered with a dense growth of plants and this is where the Corydoras are found. They inhabit a wide variety of water types but tend toward soft, neutral to slightly acidic or slightly alkaline pH and 5–10 degrees of hardness. They can tolerate only a small amount of salt (some species tolerate none at all) and do not inhabit environments with tidal influences. They are often seen in shoals. Most species prefer being in groups and many species are found in schools or aggregations of hundreds or even thousands of individuals, usually of a single species, but occasionally with other species mixed in. Unlike most catfishes, which are nocturnal, these species are nocturnal while also being active during the daytime. Corydoras are capable of breathing both water and air, often swimming to the surface to quickly ingest air before re-submerging. The frequency of this air breathing behavior increases when Corydoras are exposed to water with low oxygen availability, allowing them to tolerate periods of aquatic hypoxia.
Their main food is bottom-dwelling insects and insect larvae and various worms, as well as some vegetable matter. Although no Corydoras are piscivorous, they will eat flesh from dead fishes. Their feeding method is to search the bottom with their sensory barbels and suck up food items with their mouth, often burying their snout up to their eyes.
In several species of Corydoras, it has been observed that the fishes, after initial evasive reaction to threat, lie still; this is suggested to be a form of cryptic behavior. However, it is also argued that most species do not have cryptic coloration nor freezing behavior and continue to exist, likely due to their armor and venom. A few species of Otocinclus: (O. affinis, O. flexilis, O. mimulus and O. xakriaba) are considered to be Batesian mimics of certain Corydoras species (C. diphyes, C. garbei, C. nattereri and C. paleatus, respectively). These species have bony plates of armor and strong, frequently venomous spines as defenses, making them less palatable; by mimicking these species in size and coloration, Otocinclus avoid predation.
A unique form of insemination has been described in Corydoras aeneus. When these fish reproduce, the male will present his abdomen to the female. The female will attach her mouth to the male's genital opening, creating the well-known "T-position" many Corydoras exhibit during courtship. The female will then drink the sperm. The sperm rapidly moves through her intestines and is discharged together with her eggs into a pouch formed by her pelvic fins. The female can then swim away and deposit the pouch somewhere else alone. Because the T-position is exhibited in other species than just C. aeneus, it is likely that this behavior is common in the genus.

## In the aquarium

The genus is well known among aquarists for its many ornamental species. Corydoras are quite placid and well suited to tropical freshwater community aquariums, as they get along well with most other species and are not aggressive. They are recommended to be kept in shoals of four to six or more. Corydoras are mostly bottom feeders, so they should be offered sinking pellets as well as supplements of live and frozen foods. If flake foods are used, care should be taken to prevent all food from being eaten by faster moving fish at the higher levels of the tank.
Most Corydoras prefer water with a slightly basic pH between 7 and 8, and temperatures between 72–78 °F (22–26 °C) They do not do well in fish tanks with high nitrate levels. This ion leads to the infection of the barbels, which will shorten and become useless. The barbels may also be affected by constant contact with a sharp substrate. Contrary to popular belief, these fish can be kept in a tank with gravel without affecting their barbels, as long as there are no sharp edges on the gravel, although they do prefer sand substrate. They are more likely to thrive if there is an open area of substrate on the bottom of the tank where they can obtain submerged food. It is a myth that salt cannot be used on this species of fish as a means of parasite medication. Salt can be added to the water of the Corydoras catfish in order to rid the fish of ich. These fish are fairly easy to keep, being peaceful, hardy, active and entertaining. Occasionally they will dart to the surface, sticking their snout above the water for an instant to take a breath of air. This behavior is perfectly normal and is not an indication that anything is wrong with the fish. However, if this is done in excess, it can indicate poor water conditions.
Where investigated, Corydoras sp. have been shown to be diurnal and crepuscular rather than nocturnal and activity can even peak at twilight. Corydoras are a very popular choice for a community aquarium and are widely kept throughout the world. Between the years of 2006 and 2015, over 8,600,000 Corydoras were exported from the state of Amazonas, accounting for roughly 6.06% of the state's ornamental fish exports during this time. Their longevity in the aquarium is noteworthy; C. aeneus is said to have lived 27 years in captivity and 20 years is not uncommon.

## Species

As of April 2024, there are currently 171 extant species in this genus (as recognized by FishBase), as well as one known extinct species:
* Corydoras acrensis Nijssen, 1972 (Acre corydoras)
* Corydoras acutus Cope, 1872 (Black-top corydoras)
* Corydoras adolfoi W. E. Burgess, 1982 (Adolfo's catfish)
* Corydoras aeneus (T. N. Gill, 1858) (Bronze corydoras)
* Corydoras agassizii Steindachner, 1876 (Agassiz's corydoras)
* Corydoras albolineatus Knaack, 2004 (White stripe cory)
* Corydoras amandajanea Sands, 1995 (Amanda Jane's cory)
* Corydoras amapaensis Nijssen, 1972 (Amapa corydoras)
* Corydoras ambiacus Cope, 1872 (Spotted corydoras)
* Corydoras amphibelus Cope, 1872 (Mystery cory)
* Corydoras apiaka Espíndola, M. R. S. Soares, L. R. Rosa & M. R. Britto, 2014 (Arinos cory)
* Corydoras approuaguensis Nijssen & Isbrücker, 1983 (Zebratail cory)
* Corydoras araguaiaensis Sands, 1990 (Araguaia cory)
* Corydoras arcuatus Elwin, 1938 (Skunk corydoras)
* Corydoras areio Knaack, 2000 (Hump cory)
* Corydoras armatus (Günther, 1868) (Sail cory)
* Corydoras atropersonatus S. H. Weitzman & Nijssen, 1970 (Fairy catfish)
* Corydoras aurofrenatus C. H. Eigenmann & C. H. Kennedy, 1903 (Goldhead cory)
* Corydoras axelrodi Rössel, 1962 (Pink corydoras)
* Corydoras baderi Geisler, 1969 (Road cory)
* Corydoras benatti Espíndola, Tencatt, Pupo, Villa-Verde & Britto, 2018 (Speckled xingu cory)
* Corydoras bicolor Nijssen & Isbrücker, 1967 (Two-tone cory)
* Corydoras bifasciatus Nijssen, 1972 (Two-stripe corydoras)
* Corydoras bilineatus Knaack, 2002 (White-striped corydoras)
* Corydoras blochi Nijssen, 1971 (Spotback corydoras)
* Corydoras boehlkei Nijssen & Isbrücker, 1982 (Caura cory)
* Corydoras boesemani Nijssen & Isbrücker, 1967 (Boeseman's catfish)
* Corydoras bondi Gosline, 1940 (Black-stripe corydoras)
* Corydoras breei Isbrücker & Nijssen, 1992 (Avanavero cory)
* Corydoras brevirostris Fraser-Brunner, 1947 (Spotted collar cory)
* Corydoras britskii (Nijssen & Isbrücker, 1983) (Britski's catfish)
* Corydoras brittoi Tencatt & Ohara, 2016
* Corydoras burgessi H. R. Axelrod, 1987 (Burgess's catfish)
* Corydoras carlae Nijssen & Isbrücker, 1983 (Carla's cory)
* Corydoras caudimaculatus Rössel, 1961 (Tailspot corydoras)
* Corydoras cervinus Rössel, 1962 (Deer-faced cory)
* Corydoras cochui G. S. Myers & S. H. Weitzman, 1954 (Barredtail corydoras)
* Corydoras colossus Tencatt, S. Grant, Bentley, 2023 (Colossus cory)
* Corydoras concolor S. H. Weitzman, 1961 (Slate cory)
* Corydoras condiscipulus Nijssen & Isbrücker, 1980 (Schoolmate cory)
* Corydoras copei Nijssen & Isbrücker, 1986 (Lake cory)
* Corydoras coppenamensis Nijssen, 1970 (Chopstick cory)
* Corydoras coriatae W. E. Burgess, 1997 (Hermit cory)
* Corydoras cortesi D. M. Castro, 1987
* Corydoras costai Ottoni, Barbosa & Katz, 2016
* Corydoras crimmeni S. Grant, 1997 (Blackwater cory)
* Corydoras cruziensis Knaack, 2002 (Santa Cruz cory)
* Corydoras crypticus Sands, 1995 (Yellow head cory)
* Corydoras davidsandsi B. K. Black, 1987 (Sands's corydoras)
* Corydoras delphax Nijssen & Isbrücker, 1983 (False blochi catfish)
* Corydoras difluviatilis M. R. Britto & R. M. C. Castro, 2002 (Sparano cory)
* Corydoras diphyes Axenrot & S. O. Kullander, 2003 (Variable cory)
* Corydoras duplicareus Sands, 1995 (Duplicate corydoras, broadstripe cory)
* Corydoras ehrhardti Steindachner, 1910 (Olive cory)
* Corydoras elegans Steindachner, 1876 (Elegant corydoras)
* Corydoras ellisae Gosline, 1940 (Two point cory)
* Corydoras ephippifer Nijssen, 1972 (Saddle corydoras)
* Corydoras eques Steindachner, 1876 (Horseman's corydoras)
* Corydoras esperanzae D. M. Castro, 1987 (Orocue cory)
* Corydoras evelynae Rössel, 1963 (Evelyn's cory)
* Corydoras eversi Tencatt & M. R. Britto, 2016 (Guarana cory)
* Corydoras filamentosus Nijssen & Isbrücker, 1983 (Filament cory)
* Corydoras flaveolus R. Ihering (pt), 1911 (Yellow cory)
* Corydoras fowleri J. E. Böhlke, 1950 (Fowler's cory)
* Corydoras froehlichi Tencatt, M. R. Britto & Pavanelli, 2016
* Corydoras fulleri Tencatt, Evers, H-G & Britto 2021. (Fuller's cory)
* Corydoras garbei R. Ihering, 1911 (Bahia cory)
* Corydoras geoffroy Lacépède, 1803 (Wolf cory)
* Corydoras geryi Nijssen & Isbrücker, 1983 (Bolivian cory)
* Corydoras gladysae Calviño & F. Alonso, 2010 (Gladys's cory)
* Corydoras gomezi D. M. Castro, 1986 (Leticia cory)
* Corydoras gossei Nijssen, 1972 (Pale-spotted corydoras)
* Corydoras gracilis Nijssen & Isbrücker, 1976 (Shy cory)
* Corydoras griseus Holly, 1940 (Grey corydoras)
* Corydoras gryphus Tencatt, M. R. Britto & Pavanelli, 2014 (Dragon-fin cory)
* Corydoras guapore Knaack, 1961 (Guapore corydoras)
* Corydoras guianensis Nijssen, 1970 (Light cory)
* Corydoras habrosus S. H. Weitzman, 1960 (Salt and pepper catfish)
* Corydoras haraldschultzi Knaack, 1962 (Mosaic corydoras)
* Corydoras hastatus C. H. Eigenmann & R. S. Eigenmann, 1888 (Dwarf corydoras)
* Corydoras hephaestus Ohara, Tencatt & M. R. Britto, 2016 (Fireball cory)
* Corydoras heteromorphus Nijssen, 1970 (White cory)
* Corydoras iiap
* Corydoras imitator Nijssen & Isbrücker, 1983 (Imitator cory)
* Corydoras incolicana W. E. Burgess, 1993 (Icana cory)
* Corydoras isbrueckeri Knaack, 2004 (Brazil longnose cory)
* Corydoras julii Steindachner, 1906 (Julii corydoras)
* Corydoras kanei S. Grant, 1998 (Kane's cory)
* Corydoras knaacki Tencatt & Evers, 2016 (Knaacks cory)
* Corydoras lacerdai Hieronimus, 1995 (Lacerda's cory)
* Corydoras lacrimostigmata Tencatt, M. R. Britto & Pavanelli, 2014 (Tearful cory)
* Corydoras lamberti Nijssen & Isbrücker, 1986 (Lambert's cory)
* Corydoras latus N. E. Pearson, 1924 (Wide cory)
* Corydoras leopardus G. S. Myers, 1933 (Leopard corydoras)
* Corydoras leucomelas C. H. Eigenmann & W. R. Allen, 1942 (False spotted catfish)
* Corydoras longipinnis Knaack, 2007 (Long-finned cory)
* Corydoras loretoensis Nijssen & Isbrücker, 1986 (Loreto cory)
* Corydoras loxozonus Nijssen & Isbrücker, 1983 (Dirty bandit cory)
* Corydoras lymnades Tencatt, Vera-Alcaraz, M. R. Britto & Pavanelli, 2013 (Nose stribed cory)
* Corydoras maculifer Nijssen & Isbrücker, 1971 (Dotted corydoras)
* Corydoras mamore Knaack, 2002 (Marmore cory)
* Corydoras melanistius Regan, 1912 (Blue-spotted corydoras)
* Corydoras melanotaenia Regan, 1912 (Green-gold catfish)
* Corydoras melini Lönnberg & Rendahl (de), 1930 (Bandit corydoras)
* Corydoras metae C. H. Eigenmann, 1914 (Masked corydoras)
* Corydoras micracanthus Regan, 1912 (Andes cory)
* Corydoras microcephalus Regan, 1912 (Peppered Argentina cory)
* Corydoras multimaculatus Steindachner, 1907 (Many-spotted cory)
* Corydoras multiradiatus (Orcés-V. (es), 1960) (Hognosed brochis)
* Corydoras nanus Nijssen & Isbrücker, 1967 (Little corydoras)
* Corydoras napoensis Nijssen & Isbrücker, 1986 (Rio Napo cory)
* Corydoras narcissus Nijssen & Isbrücker, 1980 (Narcissus corydoras)
* Corydoras nattereri Steindachner, 1876 (Blue corydoras)
* Corydoras negro Knaack, 2004 (Rio Negro cory)
* Corydoras nijsseni Sands, 1989 (Nijssen's corydoras)
* Corydoras noelkempffi Knaack, 2004 (Meander cory)
* Corydoras oiapoquensis Nijssen, 1972 (Flag-tailed panda cory)
* Corydoras ornatus Nijssen & Isbrücker, 1976 (Ornate cory)
* Corydoras orphnopterus S. H. Weitzman & Nijssen, 1970 (Rabbit cory)
* Corydoras ortegai M. R. Britto, F. C. T. Lima & M. H. Hidalgo, 2007 (Loreto panda cory)
* Corydoras osteocarus J. E. Böhlke, 1951 (Bonehead cory)
* Corydoras ourastigma Nijssen, 1972 (Long-nosed smudgespot cory)
* Corydoras oxyrhynchus Nijssen & Isbrücker, 1967 (Sharp-nosed cory)
* Corydoras paleatus (L. Jenyns, 1842) (Peppered corydoras)
* Corydoras panda Nijssen & Isbrücker, 1971 (Panda corydoras)
* Corydoras pantanalensis Knaack, 2001 (Pantanal cory)
* Corydoras paragua Knaack, 2004 (Paragua cory)
* Corydoras parallelus W. E. Burgess, 1993 (Two-line cory)
* Corydoras pastazensis S. H. Weitzman, 1963 (Pastaza corydoras)
* Corydoras paucerna Knaack, 2004 (Cuddly cory)
* Corydoras pavanelliae Tencatt & Ohara, 2016
* Corydoras petracinii Calviño & F. Alonso, 2010 (Petracini's cory)
* Corydoras pinheiroi Dinkelmeyer, 1995 (Mario's cory)
* Corydoras polystictus Regan, 1912 (Fine-spotted cory)
* Corydoras potaroensis G. S. Myers, 1927 (Potaro cory)
* Corydoras pulcher Isbrücker & Nijssen, 1973 (Pretty corydoras)
* Corydoras punctatus (Bloch, 1794) (Spot-fin corydoras)
* Corydoras pygmaeus Knaack, 1966 (Pygmy corydoras)
* Corydoras rabauti La Monte, 1941 (Rusty corydoras)
* Corydoras reticulatus Fraser-Brunner, 1938 (Reticulated corydoras)
* Corydoras reynoldsi G. S. Myers & S. H. Weitzman, 1960 (Bumblebee cory)
* Corydoras robineae W. E. Burgess, 1983 (Banner-tail corydoras)
* Corydoras robustus Nijssen & Isbrücker, 1980 (Robust cory)
* Corydoras sanchesi Nijssen & Isbrücker, 1967 (Gojo cory)
* Corydoras saramaccensis Nijssen, 1970 (Saramaccensis cory)
* Corydoras sarareensis Dinkelmeyer, 1995 (Sarare cory)
* Corydoras schwartzi Rössel, 1963 (Schwartz's catfish)
* Corydoras semiaquilus S. H. Weitzman, 1964 (Peru black cory)
* Corydoras septentrionalis Gosline, 1940 (Northern kongnose cory)
* Corydoras serratus Sands, 1995 (Sawtooth cory)
* Corydoras seussi Dinkelmeyer, 1996 (Seuss's cory)
* Corydoras similis Hieronimus, 1991 (Smudgespot cory)
* Corydoras simulatus S. H. Weitzman & Nijssen, 1970 (Olga cory)
* Corydoras sipaliwini Hoedeman, 1965 (Nail cory)
* Corydoras sodalis Nijssen & Isbrücker, 1986 (False network catfish)
* Corydoras solox Nijssen & Isbrücker, 1983 (Club cory)
* Corydoras spectabilis Knaack, 1999 (Millennium cory)
* Corydoras spilurus Norman, 1926 (Pink-throat corydoras)
* Corydoras splendens (Castelnau, 1855) (Emerald corydoras)
* Corydoras steindachneri Isbrücker & Nijssen, 1973 (Paraná corydoras)
* Corydoras stenocephalus C. H. Eigenmann & W. R. Allen, 1942 (Huangana cory)
* Corydoras sterbai Knaack, 1962 (Sterba's corydoras)
* Corydoras surinamensis Nijssen, 1970 (Suriname cory)
* Corydoras sychri S. H. Weitzman, 1960 (Sychr's catfish)
* Corydoras treitlii Steindachner, 1906 (Long-snout corydoras)
* Corydoras trilineatus Cope, 1872 (Three-stripe corydoras)
* Corydoras tukano M. R. Britto & F. C. T. Lima, 2003 (Tukano cory)
* Corydoras undulatus Regan, 1912 (Wavy catfish)
* Corydoras urucu M. R. Britto, Wosiacki & Montag, 2009 (Urucu cory)
* Corydoras virginiae W. E. Burgess, 1993 (Miguelito corydoras)
* Corydoras vittatus Nijssen, 1971 (Stripy cory)
* Corydoras weitzmani Nijssen, 1971 (Two-saddle corydoras)
* Corydoras xinguensis Nijssen, 1972 (Xingu corydoras)
* Corydoras zawadzkii Tencatt & Ohara, 2016
* Corydoras zygatus C. H. Eigenmann & W. R. Allen, 1942 (Black-band catfish)
* †Corydoras revelatus Cockerell, 1925—Fossil species from the Late Paleocene