INVESTIGATIONS IN FISH CONTROL

29. Efficacy of Methylpentynol as an Anesthetic 

on Four Salmonids

30. Toxicity of Methylpentynol 

to Selected Fishes

31. Annotated Bibliography on Methylpentynol

United States Department of the Interior

Fish and Wildlife Service 

Bureau of Sport Fisheries and Wildlife
INVESTIGATIONS IN FISH CONTROL

Investigations in Fish Control, published by the Bureau of Sport Fisheries and Wildlife, include reports on the results of work at the Bureau's Fish Control Laboratories at La Crosse, 

Wis., and Warm Springs, Ga., and reports of other studies related to that work. Though each 

report is regarded as a separate publication, several may be issued under a single cover, for 

economy.

Current reports in this series are 

(Reports 1 and 2 are in one cover.)

1. Laboratories and Methods for Screening Fish-Control Chemicals, by Robert E. Lennon 

and Charles R. Walker. 1964. 15 p.

2. Preliminary Observations on the Toxicity of Antimycin A to Fish and Other Aquatic 

Animals, by Charles R. Walker, Robert E. Lennon, and Bernard L. Berger. 1964. 18 p.

(Reports 3 through 8 are in one cover.)

3. Minimum Lethal Levels of Toxaphene as a Piscicide in North Dakota Lakes, by Dale L. 

Henegar. 1966. 16 p.

4. Effects of Toxaphene on Plankton and Aquatic Invertebrates in North Dakota Lakes, by 

Robert G. Needham. 1966. 16 p.

5. Growth Rates of Yellow Perch in Two North Dakota Lakes After Population Reduction with 

Toxaphene, by Donald C. Warnick. 1966. 9 p.

6. Mortality of Some Species of Fish to Toxaphene at Three Temperatures, by Mahmoud 

Ahmed Mahdi. 1966. 10 p.

7. Treatment of East Bay, Alger County, Michigan, with Toxaphene for Control of Seal Lampreys, by William E. Gaylord and Bernard R. Smith. 1966. 7 p.

8. Effects of Toxaphene on Fishes and Bottom Fauna of Big Kitoi Creek, Afognak Island, 

Alaska, by William R. Meehan and William L. Sheridan. 1966. 9 p.

(Reports 9 through 11 are in one cover.)

9. Relation of Chemical Structure to Fish Toxicity in Nitrosalicylanilides and Related Compounds, by Charles R. Walker, Roland J. Starkey, and Leif L. Marking. 1966. 12 p.

10. Evaluation of p,p'-DDT as a Reference Toxicant in Bioassays, by Leif L. Marking.

1966. 10 p.

11. Evaluation of an Electronic Method of Measuring Hematocrits of Fish, by Richard A. 

Schoettger and Arnold M. Julin. 1966. lip.

(Reports 12 through 17 are in one cover.)

12. Toxicity of MS-222 to Selected Fishes, by Leif L. Marking. 1967. 10 p.

13. Efficacy of MS-222 as an Anesthetic on Four Salmonids, by Richard A. Schoettger and 

Arnold M. Julin. 1967. 15 p.

14. Method for Determining MS-222 Residues in Fish, by Charles R. Walker and Richard A. 

Schoettger. 1967. 10 p.

15. Residues of MS-222 in Four Salmonids Following Anesthesia, by Charles R. Walker and 

Richard A. Schoettger. 1967. lip.

16. Annotated Bibliography on MS-222, by Richard A. Schoettger. 1967. 15 p.

17. MS-222 as an Anesthetic for Channel Catfish: Its Toxicity, Efficacy, and Muscle Residues, 

by Richard A. Schoettger, Charles R. Walker, Leif L. Marking, and Arnold M. Julin.

1967. 14 p.

Fish Control Laboratories

Bureau of Sport Fisheries and Wildlife

U.S. Department of the Interior

P.O. Box 862

La Crosse, Wisconsin 54602

Continued on inside back cover 
INVESTIGATIONS IN FISH CONTROL

29. Efficacy of Methylpentynol as an Anesthetic on Four Salmonids

By Robert M. Howland and Richard A. Schoettger

30. Toxicity of Methylpentynol to Selected Fishes 

By Leif L. Marking

31. Annotated Bibliography on Methylpentynol 

By Gerald E. Svendsen

UNITED STATES DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

Bureau of Sport Fisheries and Wildlife 

Washington, D.C. February 1969

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 - Price 35 cents
IN THIS COVER

Pages

Efficacy of Methylpentynol as an Anesthetic on Four Salmonids,

by Robert M. Howland and Richard A. Schoettger. ......... 1-11

Toxicity of Methylpentynol to Selected Fishes, by Leif L.

Marking. .................................... 1-7

Annotated Bibliography on Methylpentynol, by Gerald E.

Svendsen .................................... 1-7

ii
INVESTIGATIONS IN FISH CONTROL

29. Efficacy of Methylpentynol as an Anesthetic 

on Four Salmonids

By Robert M. Howland and Richard A. Schoettger

UNITED STATES DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

Bureau of Sport Fisheries and Wildlife 

Washington, D.C. February 1969
CONTENTS

Page

Abstract....................................... 3

Methods and materials ............................. 4

Results. ....................................... 4

Efficacy .................................... 4

Effects of water quality.......................... 9

Repeated use of solutions. ........................ 9

Effects of repeated anesthetization .................. 9

Discussion ..................................... 9

Conclusions. .................................... 9

References ..................................... 10
EFFICACY OF METHYLPENTYNOL AS AN ANESTHETIC 

ON FOUR SALMONIDS

By Robert M. Howland and Richard A. Schoettger, Fishery Biologists

Bureau of Sport Fisheries and Wildlife 

Fish Control Laboratory, La Crosse, Wisconsin

ABSTRACT. Effective concentrations of methylpentynol for anesthetizing 

rainbow trout, brown trout, brook trout, and lake trout were determined by a 

series of tests. Concentrations of 1.5 to 8 parts per thousand induced anesthesia in 4 to 57 minutes. Increase in water temperature accelerated anesthesia. Changes in pH or in water hardness had no significant effect on the 

rate of anesthesia. Repeated anesthesia had little effect on rate of response. 

The efficacy of anesthetic solutions was reduced by continuous use. 

Approximately 1 kilogram of rainbow trout could be effectively narcotized 

per milliliter of drug. Methylpentynol was compared with MS-222 as a fish 

anesthetic. Fifty - times as much methylpentynol was necessary to yield the 

equivalent effect of 100 parts per million of MS-222. Methylpentynol may be 

more appropriate as a sedative or soporific for salmonids than as an anesthetic.

The demand for anesthetics in stripping, 

marking, and transporting fish has led to 

experimentation with various drugs used in 

human medicine, such as methylpentynol. 

Parkhurst and Smith (1957) found that the 

compound worked well to quiet fish for stripping. Since then, a number of investigators 

have found that methylpentynol is a potent 

fish anesthetic and is also useful as a sedative in fish transport (Norris et al., 1960; 

McFarland, 1959, 1960; Carlson, 1965). However, fish entering anesthesia may struggle 

violently and are not completely immobilized 

under narcosis, according to reports cited by 

Bell (1964). They may also go into respiratory 

arrest, thereby making the maintenance of 

anesthesia difficult (Klontz, 1964).

Methylpentynol (3-Methyl- l-pentyn-3-ol) 

was originally patented in 1913 by the Bayer 

Company of Germany. Some common synonyms 

of the compound include methylparafynol, 

Oblivon, and Dormison (Stecher et al., 1960). 

During the early 1950's it was introduced as a 

hypnotic in human medicine (Margolin et al.,

1951; Hirsh and Orsinger, 1952; andPerlman 

and Johnson, 1952), but because of its side - 

effects and questionable efficacy (Lasagna, 

1954; Marley, 1958; Kennedy and Marley, 

1959; Goodman and Gilman, 1965) it had only 

a brief period of popularity.

Lennon (1967) discussed recent amendments to the Federal Food, Drug, and Cosmetic Act which require that chemicals used 

on fish be cleared and labeled for specific 

uses. We elected to investigate methylpentynol 

as one of the anesthetics because the treated 

fish may be eaten by humans. Information on 

the toxicity of methylpentynol to fish, its efficacy as a fish anesthetic, and its residues 

in fish tissues is necessary to obtain clearance.

We centered our investigation on the efficacy of methylpentynol, specifically the concentrations for practical use on rainbow trout, 

brown trout, brook trout, and lake trout. We 

also measured the effects of water quality, 

size of fish, repeated exposure, and reuse of 

anesthetic solutions on efficacy.
Investigations in Fish Control 29: Bureau of Sport Fisheries and Wildlife

METHODS AND MATERIALS

We purchased a technical grade (Eastman 

grade) of methylpentynol from the Eastman 

Kodak Company, Rochester, N.Y. Its efficacy 

as a fish anesthetic was measured with trout 

of two size-ranges: 2 to 6 inches and 7 to 12 

inches (table 1). The methods of preparing 

test solutions, waters of various qualities, 

controlling temperature, and acclimating the 

test fish were as described by Schoettger and 

Julin (1967).

The behavioral responses of trout to methylpentynol conformed reasonably well to those 

reported for fish exposed to MS-222 (Schoettger 

and Julin, 1967). Effectiveness of the drug was 

evaluated by placing the trout in various concentrations and recording the times for all of 

the test fish to exhibit the following behavioral 

responses: sedation; total loss of equilibrium, 

stage 11; and loss of reflex. We also recorded 

the time required for the first fish to enter 

medullary collapse. When all fish reached 

this stage, they were returned to well water 

for recovery.

Ten fish were used to bioassay each concentration, and in most instances the experiments were replicated. The amenability of 

trout to handling when in the deeper stages of 

narcosis was tested by removing them briefly 

from the solutions, and simulating the stripping procedure.

TABLE 1. Species and sources of test fish

Species Length 

(inches) Source

Rainbow trout 2-6 Raised at Fish Control 

(Salmo gairdneri) Laboratory; eggs from

Brown trout 

(Salmo trutta)

Brook trout

(Salvelinus fontinalis)

Lake trout

(Salvelinus namaycush)

Rainbow Ranches, Spokane, 

Washington

7-12 NFH1 , Manchester, Iowa

2-6 Raised at Fish Control 

Laboratory; eggs from 

McNenny NFH, Spearfish, 

South Dakota

7-12 NFH, Manchester, Iowa

2-6 Raised at Fish Control 

Laboratory; eggs from 

SFH2 , Osceola, Wisconsin

2-6 NFH, Jordan River, Elmira, 

Michigan

The reusability of methylpentynol solutions 

was determined by anesthetizing fresh groups 

of five rainbow trout, 7 to 12 inches long, in 

5 liters of a 5 p.p.t. (part per thousand) solution at 12°C. This concentration anesthetizes 

rainbow trout to loss of reflex within 2 minutes. Fresh groups of fish were exposed until 

the drug was no longer effective within 2 minutes. We then calculated the kilograms of trout 

anesthetized per milliliter of the drug.

The effect of repeated exposure on the susceptibility of rainbow trout to methylpentynol 

was measured by anesthetizing 10 individuals 

daily for 10 consecutive days at 12°C. They 

were narcotized to loss of reflex in a concentration of 5 p.p.t. and then placed in flowing 

well water for recovery. Each day, the responses of single-exposure and untreated control fish were observed in conjunction with 

the group undergoing repeated exposure. After 

10 days, we made a gross examination for 

pathology in the repeatedly exposed fish, a 

group treated only once, and an untreated 

group.

RESULTS

Efficacy

1 National Fish Hatchery

2 State Fish Hatchery

Methylpentynol was 100 percent effective at 

concentrations of 1.5 to 8 p.p.t. for anesthetizing rainbow trout, brown trout, brook trout, 

and lake trout (tables 2, 3, 4, 5). These levels 

induce total loss of equilibrium, stage II, 

within 31.0 to 0.8 minutes respectively, depending on temperature, species, and size of 

fish. Concentrations outside this range either 

were ineffective or produced narcosis at rates 

which would be relatively impractical for 

most fish-handling operations.

Methylpentynol is considerably less potent 

as a fish anesthetic than MS-222 (McFarland, 

1959). MS-222 narcotizes the species used in 

this study within 2 to 3 minutes at concentrations of about 100 p.p.m. at 12° C. (Schoettger 

and Julin, 1967). We found that at least 5,000 

p.p.m. of methylpentynol were required to 

produce a similar effect; this concentration 

anesthetized the most resistant individuals in
Howland and Schoettger: Efficacy of Methylpentynol as an Anesthetic on Four Salmonids

TABLE 2.--Efficacy of methylpentynol on two sizes of rainbow trout at three temperatures

Concentration 

(p.p.t.)

1.5........

1.5........

2.0........

Do.........

2.0........

Do

3.0........

Do.........

3.0........

Do.........

4.0. .......

Do.........

Do.........

4.0........

Dn

Do.........

5.0........

Do.........

Do.........

5.0........

Do.........

Do.........

6.0........

Do.........

6.0........

Tin

7.0........

Do.........

7.0........

Do.........

8.0........

Do.........

8.0........

Do.........

Temperature 

(°G.)

17 

17

12 

17

12

17

12 

17

12 

17

7 

12 

17

7 

12 

17

7 

12 

17

7 

12 

17

7 

12

7 

12

7 

12

7 

12

7 

12

7 

12

Fish

Length 

(inches)

2-6 

7-12

2-6 

2-6

7-12 

7-12

2-6 

2-6

7-12 

7-12

2-6 

2-6 

2-6

7-12 

7-12 

7-12

2-6 

2-6 

2-6

7-12 

7-12 

7-12

2-6 

2-6

7-12 

7-12

2-6 

2-6

7-12 

7-12

2-6 

2-6

7-12 

7-12

Number

20 

20

10 

20

20 

20

10 

20

20 

20

20 

10 

20

20 

20 

20

20 

15 

20

20 

20 

20

20 

10

20 

20

20 

10

20 

20

20 

10

20 

20

Mean induction time (minutes) for Saf

All fish into

Stage A1

31.0 

18.0

23.0 

7.8

18.8 

6.3

8.3 

3.0

4.8 

3.3

12.5 

4.3 

2.0

11.5 

4.0 

1.8

8.5 

2.8 

1.3

8.3 

2.0 

1.3

4.3 

1.5

6.3 

1.5

4.3 

1.0

4.5 

1.3

3.3 

0.8

4.3 

1.0

Stage B 2

81.5 

19.0

52.5 

16.5

22.3 

9.0

15.8 

6.0

8.0 

5.0

19.8 

8.0 

2.8

18.8 

6.5 

3.0

12.3

5.3 

2.3

9.8 

2.5 

2.5

7.3 

3.3

8.5 

2.0

7.8 

2.0

6.5 

1.8

4.5 

1.3

5.3 

1.8

Stage C 3 G/A"

46.0 1.5 

15.5 0.9

35.8 1.6 

12.8 1.6

23.3 1.2 

8.3 1.3

15.8 1.9 

5.5 1.8

9.0 1.9 

4.5 1.4

20.3 1.6 

8.3 1.9 

2.8 1.4

14.0 1.2 

4.5 1.1 

3.5 2.0

12.0 1.4 

6.5 2.4 

2.5 2.0

9.0 1.1 

3.0 1.5 

2.8 2.2

8.5 2.0 

3.3 2.2

7.3 1.2 

2.5 1.7

6.8 1.6 

2.8 2.8

5.5 1.2 

2.5 2.0

5.5 1.7 

2.5 3.3

5.5 1.3 

2.3 2.2

ety Recovery

Mean time 

G/B5 (minutes)

0.6 8.0 

0.8 6.3

0.7 17.0 

0.8 10.8

1.0 9.5 

0.9 5.0

1.0 17.0 

0.9 5.3

1.1 6.5 

0.9 6.0

1.0 27.8 

1.0 14.5 

1.0 5.0

0.7 15.3 

0.7 6.8 

1.2 6.8

1.0 32.8 

1.2 15.8 

1.0 8.5

0.9 13.8 

1.2 6.5 

1.1 6.8

1.2 25.5 

1.0 16.3

0.9 15.3 

1.3 7.0

0.9 28.3 

1.4 17.8

0.8 17.3 

1.4 8.3

1.2 25.8 

2.0 17.5

1.0 18.3 

1.3 8.5

Percent

65 

95

90 

90

80 

100

100 

100

100 

100

100 

100 

100

100 

100 

100

100 

100 

95

100 

100 

100

100 

100

100 

100

100 

100

100 

100

90 

100

100 

100

1 Total loss of equilibrium, stage II 

2 Total loss of reflex 

3 Medullary collapse 

* Time for Stage C divided by time for Stage A

groups of 2- to 6-inch brown trout and lake 

trout within 3.5 minutes and the least resistant individuals among 7- to 12-inch rainbow 

trout and brown trout within 2 minutes. The 

greater sensitivity of the larger fish is even 

more apparent at lower concentrations (tables

2 and 3). In our opinion the size-sensitivity 

relation may not be valid. Large and small 

rainbow and brown trout were obtained from 

different sources (table 1); consequently interaction between size and strain may be reflected in the results.
Investigations in Fish Control 29: Bureau of Sport Fisheries and Wildlife

TABLE 3. --Efficacy of methylpentynol on brown trout of two sizes at three temperatures

Concentration 

(p.p.t.)

1.5........

1.5........

2.0........

Do.........

2.0........

Do.........

3.0........

Do.........

Hn

3.0........

Do.........

Do.........

4.0........

Do.........

Do.........

4.0. .......

Do.........

Do.........

5.0........

Do.........

Do.........

5.0........

Do.........

Do.........

6.0........

Do.........

6.0........

Do.........

7.0........

7.0........

8.0........

8.0........

Temperature

(°c.)

17 

17

12 

17

12 

17

7 

12 

17

7 

12 

17

7 

12 

17

7 

12 

17

7 

12

17

7 

12 

17

7 

12

7 

12

7 

7

12 

12

Fish

Length 

( inches )

2-6 

7-12

2-6 

2-6

7-12 

7-12

2-6 

2-6 

2-6

7-12 

7-12 

7-12

2-6 

2-6 

2-6

7-12 

7-12 

7-12

2-6 

2-6 

2-6

7-12 

7-12 

7-12

2-6 

2-6

7-12 

7-12

2-6 

7-12 

2-6 

7-12

Number

20 

20

20 

20

20 

20

20 

20 

20

10 

20 

20

20 

20 

20

20 

20 

20

20 

20 

20

20 

20 

20

20 

20

20 

20

20 

20 

20 

20

Mean induction time (minutes) for Saf

All fish into

Stage A1

20.3 

11.3

12.8 

6.8

11.8

5.0

20.3 

10.0 

3.0

17.5 

6.0 

2.3

9.0 

5.0 

2.0

8.5 

4.0 

1.0

7.3 

3.5 

1.5

4.5 

2.0 

0.5

4.0 

1.8

3.0 

1.5

3.5 

2.3 

1.3 

1.3

Stage B 2

45.0 

42.0

26.5 

15.5

51.0 

9.0

35.0 

13.8 

4.5

28.5 

9.5 

4.3

14.8 

7.0 

2.5

16.8 

8.5 

1.3

10.5 

4.8 

2.0

9.5 

3.8 

0.8

6.5 

2.5

7.5 

2.3

6.3 

5.8 

1.8 

2.0

First fish into

Stage C' C/A"

26.8 1.3 

27.8 2.5

19.3 1.5 

12.8 1.9

28.3 2.4 

7.8 1.6

29.3 1.4 

11.3 1.1 

4.8 1.6

35.5 2.0 

9.3 1.5 

5.0 2.2

11.8 1.3 

5.5 1.1

3.0 1.5

13.0 1.5 

7.0 1.8 

2.0 2.0

10.8 1.5 

5.0 1.4 

2.5 1.7

8.3 1.8 

4.5 2.3 

11.3 2.5

5.3 1.3 

2.5 1.4

5.8 1.9 

3.0 2.0

5.8 1.6 

5.0 2.2 

2.0 1.6 

2.8 2.2

ety Recovery

Mean time 

C/B5 (minutes)

0.6 9.5 

0.7 10.0

0.7 23.8 

0.8 6.5

0.6 38.0 

0.9 5.8

0.8 28.8 

0.8 17.3 

1.1 5.0

1.2 21.0 

1.0 11.0 

1.2 5.8

0.8 30.8 

0.8 12.8 

1.2 5.8

0.8 16.3 

0.8 10.3 

1.6 6.8

1.0 18.3 

1.1 12.8 

1.3 6.5

0.9 13.0 

1.2 11.8 

1.7 6.8

0.8 16.5 

1.0 8.5

0.8 11.0 

1.3 7.8

0.9 16.5 

0.9 14.3 

1.1 9.3 

1.4 10.8

Percent

90 

100

100 

95

85 

100

100 

90 

100

100 

100 

100

100 

100 

100

100

100 

100

100 

100 

100

100 

100 

100

100 

100

100 

100

100 

100 

100 

100

1 Total loss of equilibrium, stage II

2 Total loss of reflex

3 Medullary collapse

* Time for Stage C divided by time for Stage A

5 Time for Stage C divided by time for Stage B

Temperature had a pronounced effect on the 

efficacy of methylpentynol. To illustrate, a 

concentration of 5 p.p.t. produced loss of equilibrium in all species within 4.5 to S.5 minutes at 7 C., within 2 to 3.5 minutes at 12°, 

and within 0.5 to 1.5 minutes at 17°. In general, a change in temperature of 5°C. changed 

anesthetizing time by a factor of approximately 2 to 3.

The tractability was not consistent among 

the four salmonids when anesthetized to total 

loss of equilibrium, stage II. Lake trout and 

large rainbow trout were relatively immobile. 

The other species and sizes of fish retained 

considerable reflex activity, and were difficult to handle during simulated stripping procedures. Also, a state of total loss of equilibrium was inadequate for delicate surgical
Howland and Schoettger: Efficacy of Methylpentynol as an Anesthetic on Four Salmonids 7

TABLE 4. Efficacy of methylpentynol on brook trout at three temperatures

Concentration 

(p.p.t.)

2.0........

2.0........

3.0........

Do.........

Do.........

4.0........

Do.........

Do.........

5.0........

Do.........

Do.........

6.0........

Do.........

8.0........

Do.........

ature

12 

17

7 

12 

17

7 

12 

17

7 

12 

17

7 

12

7 

12

Fish

Length 

( inches )

2-6 

2-6

2-6 

2-6 

2-6

2-6 

2-6 

2-6

2-6 

2-6 

2-6

2-6 

2-6

2-6 

2-6

Number

20

20

20 

20 

20

20 

20 

20

20 

20 

20

20 

20

20 

20

Mean induction time (minutes) for

All fish into

Stage A1

25.0 

12.8

22.3 

13.3

6.5 

3.5 

2.5

4.8 

2.5 

1.3

3.3 

1.8

2.5 

1.3

Stage B 2

54.0 

31.0

34.5 

18.8 

9.5

12.3 

10.8 

4.0

13.8 

7.3 

4.5

8.0 

6.8

5.5 

3.5

Stage C 3

Safety

:/A4 C/B5

42.0 1.7 0.8 

28.5 2.2 0.9

34.5 1.5 1.0 

16.0 1.2 0.9 

9.8 2.0 1.0

15.5 2.4 1.3 

10.0 2.9 0.9 

4.3 1.7 1.0

13.3 2.8 1.0 

4.3 1.7 0.6 

4.0 3.2 0.9

8.3 2.5 1.0 

4.5 2.6 0.7

4.8 1.9 0.9 

2.3 1.8 0.6

Recovery

Mean time 

(minutes )

26.0 

12.5

26.3 

23.3 

9.0

23.0 

19.0 

10.5

23.5 

12.5 

11.3

21.0 

15.8

17.3 

12.0

Percent

80 

90

100 

100 

100

ICO 

100 

100

100 

100 

100

100 

100

95 

100

1 Total loss of equilibrium, stage II 

2 Total loss of reflex 

3 Medullary collapse 

4 Time for Stage C divided by time for Stage A 

5 Time for Stage C divided by time for Stage B

TABLE 5. --Efficacy of methylpentynol on lake trout at three temperatures

Concentration 

(p.p.t.)

1.5........

2.0........

Do.........

Do.........

3.0........

Do.........

Do.........

4.0........

Do.........

Do.........

5.0........

Do.........

Do.........

6.0........

Do.........

8.0........

Do

Temperature

17

7 

12

17

7 

12 

17

7 

12 

17

7 

12 

17

7

12

7

12

Fish

Length 

(inches]

2-6

2-6 

2-6 

2-6

2-6 

2-6 

2-6

2-6 

2-6 

2-6

2-6 

2-6 

2-6

2-6 

2-6

2-6 

2-6

Number

20

10 

20 

20

20 

20 

20

20 

20

20

20 

20 

20

20 

20

20 

20

Mean induction time (minutes) for

All fish into

Stage A1

31.5

33.5 

25.8 

9.5

12.8 

8.0 

1.8

9.0 

4.5 

0.8

5.8 

3.5 

0.5

3.0 

2.5

2.0 

1.0

Stage B 2

69.8

84.5 

53.0 

23.8

25.3 

15.3 

3.3

13.5 

7.3 

0.8

5.8 

4.0 

0.5

3.0 

2.5

2.0 

1.0

Stage C3

30.8

41.0 

32.5 

10.8

19.8 

12.3 

3.0

12.3 

6.8 

1.3

8.0 

5.0 

1.0

5.3

4.0

3.5 

1.5

Safety 

index

C/A4 C/B5

1.0 0.4

1.2 0.5 

1.3 0.6 

1.1 0.5

1.5 0.8 

1.5 0.8 

1.7 0.9

1.4 0.9 

1.5 0.9 

1.7 1.7

1.4 1.4 

1.4 1.3 

2.0 2.0

1.8 1.8 

1.6 1.6

1.8 1.8 

1.5 1.5

Recovery

Mean time 

(minutes)

11.0

57.3 

15.3 

7.5

26.8 

12.8 

7.5

17.5 

11.8 

4.3

14.3 

10.3 

7.0

12.3 

12.5

17.0 

12.3

Percent

60

100 

100 

50

100 

100 

35

100 

100

80

100 

100 

85

100 

100

100 

100

1 Total loss of equilibrium, stage II

2 Total loss of reflex

3 Medullary collapse

4 Time for Stage C divided by time for Stage A

5 Time for Stage C divided by time for Stage B

338-452 O - 69 -2
8 Investigations in Fish Control 29: Bureau of Sport Fisheries and Wildlife

operations on rainbow trout. (Personal communication from Dr. Joseph B. Hunn, Fishery 

Biologist, Fish Control Laboratory, La 

Crosse, Wis., October 14, 1966.)

Complete immobility of the trout can be obtained by continuing exposure to the loss-ofreflex stage. With a concentration of 5 p.p.t. 

at 12° C., loss of reflex usually occurs less 

than 3 minutes after loss of equilibrium 

(tables 2, 3, 4, 5). It occurs more rapidly at 

17 C. and more slowly at 7°. However, we 

must point out that the fish enter medullary 

collapse shortly after loss of reflex, particularly at higher concentrations and temperatures.

The relative risk of overexposing trout 

when attempting to maintain anesthesia is expressed by the safe exposure indexes shown in 

tables 2, 3, 4, and 5. The danger is obviously 

greater after the fish have entered loss of 

reflex, since the values are approximately 

1.0 or less. In other words, in a given lot of 

fish, the most susceptible individuals are 

entering medullary collapse at the time the 

most resistant fish are entering loss of reflex. 

The exposure indexes for methylpentynoltreated trout do not appear to be correlated 

with concentration, temperature, species, or 

size of fish. By way of comparison, Schoettger 

and Julin (1967) reported safe exposure indexes of 2 to 3 for similar species and sizes 

of trout anesthetized in MS-222.

The mean times for recovery of fish from 

anesthesia ranged from 4 to 57 minutes (tables 

2, 3, 4, 5). In general, recovery was most 

rapid at 17 C. and least rapid at 7 . Most 

mortalities among small rainbow trout and 

lake trout occurred after long exposures to low 

concentrations at 17 .In one instance, 35 percent of the rainbow trout died after a prolonged exposure to 1.5 p.p.t. The mortality of 

lake trout varied from 15 to 65 percent at this 

temperature, but the greatest mortalities occurred following exposures to 3 p.p.t., or less,

In all of the tests, we attempted to transfer 

the fish to well-oxygenated, circulating water 

for recovery just before their opercular 

movements ceased. With protracted exposures, 

the progression of deepening sopor in the

more sensitive fish appears to become irreversible prior to medullary collapse. This was 

revealed in preliminary trials at 17° C. when 

deaths occurred among fish which were transferred to oxygen-rich water for recovery, 

even though they displayed opercular rhythm 

at the time of removal from the anesthetic. 

The mortality was even greater upon transfer 

to unaerated, static water.

In order to avoid the rapid onset of medullary collapse associated with high concentrations, it is necessary to reduce concentration, 

thus sacrificing rapid anesthesia for longer 

handling time.

As mentioned above, there also is a risk 

when exposing trout to low concentrations for 

long periods. However, the slower rates of 

anesthesia at these levels permit greater control over exposure than at higher concentrations.

A good compromise between the rate of 

anesthesia and handling time is achieved at 

concentrations between 2 and 4 p.p.t. at 12° C. 

These relations are demonstrated in figure 1. 

The greatest changes in time to loss of equilibrium, stage II, loss of reflex and medullary 

collapse with concentration occur between 2 

and 4 p.p.t. Therefore, depending on the needs,

Loss of equilibrium, stage n 

Loss of reflex 

Medullary collapse 

Mean recovery time 

from medullary collapse

SELECTED CONCENTRATION OF METHYLPENTYNOL (RRT.)

Figure 1. Mean exposures required to induce various 

stages of anesthesia in trout at 12° C. for selected 

concentrations of methylpentynol. Curves for the 

response times were derived from the average of 

response times at each concentration for various 

species and sizes of trout.
Howland and Schoettger: Efficacy of Methylpentynol as an Anesthetic on Four Salmonids 9

the fishery worker can modify the concentration to produce the type or rate of anesthesia 

and handling time to meet his requirements. 

However, he also must consider the effects of 

temperature on efficacy in making an estimate 

of effective concentrations a factor of about 

2 to 3 occurs for each 5°C. change in temperature.

Effects of Water Quality

The efficacy of methylpentynol was neither 

enhanced nor decreased in bioassays on rainbow trout at 12°C. in solutions with pH's of 5, 

7, and 9, and those with total hardnesses of 

10, 42, and 180 p.p.m. as CaCOs.

Repeated Use of Solutions

Five liters of a 5-p.p.t. solution of methylpentynol effectively anesthetized 260 rainbow 

trout, 7 to 12 inches long, at 12°C. The time 

required to anesthetize additional fish increased with each introduction. Thus, approximately 1 kilogram of rainbow trout can be 

anesthetized effectively per milliliter of drug. 

Meister and Ritzi (1958) reported that about 

14 kilograms of brook trout and 42 kilograms 

of lake trout could be anesthetized per gram 

of MS-222.

Effects of Repeated Anesthetization

The repeated exposure of fish to methylpentynol had little influence on rate of response 

to the drug. From the third exposure on, the 

fish reacted violently upon contact with the 

solution, by thrashing and leaping before narcosis. Gross internal pathological examination disclosed no detrimental effects due to 

the anesthesia.

DISCUSSION

Our investigation establishes that methylpentynol is enigmatic as a fish anesthetic. It 

is capable of inducing profound stupor in four 

salmonids and yet it also appears incapable of 

producing consistently good anesthetization. 

The condition evoked by this drug seems

closer to inebriation than anesthesia, as evidenced by such side effects as preanesthesia 

and postanesthesia lunging and untoward reactions upon reanesthetization.

We stress that intractability to handling at 

loss of equilibrium, stage II, is pronounced in 

some species. Large brown trout are difficult 

to grasp because of tail thrashing, and small 

rainbow trout, brown trout, and brook trout 

are affected to a lesser degree. Such behavior 

undoubtedly impedes a practical fish-handling 

routine.

We corroborate the findings of Bell (1964) 

and Klontz (1964) regarding the struggling of 

fish entering narcosis, incomplete immobility, and tendency toward respiratory arrest. 

An explanation for these reactions is suggested in the literature. When humans are 

given daily doses of methylpentynol in excess 

of 2 grams, the drug tends to accumulate, and 

symptoms of intoxication appear by the third 

or fourth day (Goodman and Gilman, 1965). 

Kennedy and Marley (1959) reported abnormal 

brain-wave activity with toxic phenomena during a 5-day regime in humans. Also, they 

found a correlation between the degree of electroencephalic abnormality and the amount of 

physical disturbance produced by the drug in 

patients with toxic manifestations. A high rise 

of acetylcholine in rat brains, related to the 

degree of depression, was reported by Pepeu 

(1960). Margolinetal. (1951) found that methylpentynol does not possess analgesic or anesthetic properties when tested on mice and dogs, 

and that it lacks antispasmodic action; it was 

proffered solely as a soporific in human medicine.

The nature and size of the operation should 

determine whether this relatively expensive 

drug is a practical anesthetic for use in fishery management. A preferred stage of anesthesia cannot be recommended because of the 

aforementioned shortcomings at each level.

CONCLUSIONS

1. Methylpentynol is effective for the anesthesia of rainbow trout, brown trout, brook 

trout, and lake trout at concentrations of 

1.5 to 8 p.p.t.
10 Investigations in Fish Control 29: Bureau of Sport Fisheries and Wildlife

2. The rate of anesthesia increases as the 

concentration and/or the water temperature increases. A 5°C. change in water 

temperature causes a change in the rate of 

anesthesia by a factor of 2 to 3.

3. Concentrations from 2 to 4 p.p.t. appear 

better suited for handling of fish than do 

higher levels.

4. Water quality and pH of the anesthetic 

solution have no effect on the rate of anesthesia.

5. Methylpentynol does not produce the desirable or consistent characteristics of anesthesia which are acceptable for handling 

fish. Small lake trout and large rainbow 

trout were amenable to simulated stripping procedures, while small rainbow trout, 

small brook trout, and large and small 

brown trout were not.

6. Methylpentynol is less potent than MS-222 

as a fish anesthetic. Fifty times as strong 

a solution of methylpentynol is necessary 

to yield the effect of a solution containing 

100 p.p.m., of MS-222.

7. Methylpentynol appears to be more appropriate as a sedative or soporific for salmonids than as an anesthetic.

REFERENCES

Bell, Gordon R,

1964. A guide to the properties, characteristics, 

and uses of some general anaesthetics for fish. 

Fisheries Research Board of Canada, Bulletin 

148. 4 p.

Carlson, Frank T.

1965. Susquehanna River shad study. Pennsylvania Angler, October, p. 1-7.

Kennedy, Walter A., and Edward Marley.

1959. The electroencephalographic effects of 

methylpentynol. Electroencephalography and 

Clinical Neurophysiology, vol. 11, no. 1, 

p. 59-64.

Klontz, George W.

1964. Anesthesia of fishes. ^Proceedings of the 

Symposium on Experimental Animal Anesthesiology, Brooks Air Force Base, December 14-16. 

13 p.

Lasagna, Louis.

1954. A comparison of hynotic agents. Journal of 

Pharmacology and Experimental Therapeutics, 

no. Ill, p. 9-20.

Lennon, Robert E.

1967. Clearance and registration of chemical 

tools for fisheries. Progressive Fish-Culturist, 

vol. 29, no. 4, p. 187-193.

Margolin, S., P. Perlman, F. Villani, andT. H. McGavack. 

1951. A new class of hypnotics: Unsaturatedcarbinols. Science, vol. 114, p. 384-385.

Marley, Edward.

1958. Susceptibility to methylpentynol and methylpentynol carbamate. British Medical Journal, 

Medical Memoranda, August 23, p. 493.

McFarland, William N.

1959. A study of the effects of anesthetics on the 

behavior and physiology of fishes. Publications 

of the Institute of Marine Science, University of 

Texas, vol. 6, p. 23-55.

1960. The use of anesthetics for the handling and 

the transport of fishes. California Fish and 

Game, vol. 46, no. 4, p. 407-431.

Meister, Alfred L., and Charles F. Ritzi.

1958. Effects of chloretone and MS-222 on eastern 

brook trout. Progressive Fish-Culturist, vol. 

20, no. 3, p. 104-110.

Norris, Kenneth S., Frank Brocato, Frank Calandrino, 

and William N. McFarland.

1960. A survey of fish transportation methods 

and equipment. California Fish and Game, vol. 

46, no. 1, p. 5-33.

Parkhurst, Z. E., and M. A. Smith.

1957. Various drugs as aids in spawning rainbow 

trout. Progressive Fish-Culturist, vol. 19, 

no. 1, p. 39.

Goodman, Louis S., and Alfred Gilman.

1965. The Pharmacological Basis of Therapeutics. 

Third edition. Macmillan Company, New York. 

1,785 p.

Hirsh, Harold L., and William H. Orsinger.

1952. Methylparafynol - a new type hypnotic. 

Preliminary report on its therapeutic efficacy 

and toxicity. American Practitioner, vol. 3, 

no. 1, p. 23-26.

Pepeu, Gianciarlo, and Nicholas J. Giarman.

1960. Effects of methylpentynol on acetylcholine 

in the rat's brain. Nature, vol. 186, p. 638.

Perlman, Preston L., and Carol Johnson.

1952. The metabolism of Dormison (3-Methylpentyne-ol-3, Methyl Parafynol) and methods 

for the estimation of Dormison in biological 

material. Journal of the American Pharmaceutical Association, vol. 41, no. 1, p. 13-16.
Howland and Schoettger: Efficacy of Methylpentynol as an Anesthetic on Four Salmonids 11

Schoettger, Richard A., and Arnold M. Julin. Stecher, Paul G., M. J. Finkel, O. H. Siegmund, and

1967. Investigations in Fish Control: 13. Efficacy B. M. Szafranski.

of MS-222 as an anesthetic on four salmonids. 1960. The Merck Index of Chemicals and Drugs.

U.S. Bureau of Sport Fisheries and Wildlife. Seventh edition. Merck and Company, Rahway,

15 p. N.J. 1,641 p.
INVESTIGATIONS IN FISH CONTROL

3O. Toxicity of Methylpentynol to Selected Fishes

By Leif L. Marking

UNITED STATES DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

Bureau of Sport Fisheries and Wildlife 

Washington, D.C. February 1969
CONTENTS

Page

Abstract. ...................................... 3

Methods and materials .............................. 3

Results. ....................................... 4

Species and sizes of fish ......................... 4

Effects of temperature .......................... 6

Effects of water quality.......................... 6

Discussion ..................................... 6

Conclusions. .................................... 6

References ..................................... 7
TOXICITY OF METHYLPENTYNOL TO SELECTED FISHES

By Leif L. Marking, Chemist

Bureau of Sport Fisheries and Wildlife

Fish Control Laboratory, La, Crosse, Wisconsin

Abstract. Methylpentynol was tested in 96-hour bioassays for its toxicity to rainbow trout, brown trout, brook trout, lake trout, northern pike, 

channel catfish, bluegills, largemouth bass, and walleyes. The LCSO's 

range from 660 to 1,890 parts per million at 12°C. Channel catfish are 

the most resistant and lake trout are the most sensitive. Two-inch rainbow 

trout, brown trout, and lake trout are more sensitive to methylpentynol 

than larger ones in 96-hour exposures. The drug is more toxic to bluegills at 17° than at 12° C. Toxicity was not influenced in different water 

hardnesses of 10 to 180 parts per million.

Methylpentynol (3- methyl-1 -pentyn-3-ol) 

has been used in human medicine as a hypnotic 

and sedative at oral doses of 100 to 800 milligrams (Hirsh and Or singer, 1952) and 250 

to 500 milligrams (Stecher et al., 1960). 

Overdoses, however, may produce acute psychosis, abnormalities of the nervous system, 

or coma and death in extreme cases. Since 

methylpentynol possesses no unique advantages as a human hypnotic to outweigh its disadvantages, it is no longer recommended 

(Sharpless, 1965). The oral LD50 for mice, 

rats, and guinea pigs is 600 to 900 mg./kg. 

(Margolin, Perlman, and McGavack, 1951).

Methylpentynol is a recognized anesthetic 

for fish at concentrations of 0.5 to 0.9 ml./l. 

(Klontz, 1964). Others have reported applications of the drug as a hypnotic in transporting 

fish at concentrations of 1 to 3 ml./gal. (Bell, 

1964; Carlson, 1965; Fry and Norris, 1962; 

and McFarland, 1959 and 1960). Bayliff and 

Klima (1962) reported methylpentynol toxic to 

some fish at 6 ml./gal. (approximately 1,580 

p.p.m.) and suggested it was too slow-acting 

for field use. Howland and Schoettger (1969) 

found that 1,500 to 8,000 p.p.m. of methylpentynol produced anesthesia within 4 to 57

minutes, but suggest the compound is better 

suited as a sedative than an anesthetic. As an 

anesthetic there is danger of overexposing the 

fish because of the high concentrations required to achieve rapid anesthesia.

Since fish can be overdosed with methylpentynol, we should determine its toxicity to 

fish. Amendments to the Federal Food, Drug, 

and Cosmetic act also require toxicity data to 

clear the drug for this use (Lennon, 1967). I 

have chosen to determine the toxicity of 

methylpentynol to rainbow trout, brown trout, 

brook trout, lake trout, northern pike, channel 

catfish, bluegills, largemouth bass, and walleyes with considerations to changes in temperature, water quality, and size of fish.

METHODS AND MATERIALS

Experimental fish were obtained from State 

and Federal fish hatcheries (table 1). Three 

size groups included 1- to 3-inch, 3- to 5-inch, 

and 6- to 9-inch fish. Ten fish were tested at 

each of 10 or 11 concentrations of methylpentynol in 15-liter, static bioassays according 

to the methods of Lennon and Walker (1964).
Investigations in Fish Control 30: Bureau of Sport Fisheries and Wildlife

TABLE 1. Fishes used in tests of methylpentynol

Common and scientific name Source

Rainbow trout 

(Salmo gairdneri)

Brown trout 

(Salmo trutta)

Brook trout

(Salvelinus fontinalis)

Lake trout

(Salvelinus namaycush)

Northern pike 

(Esox lucius)

Channel catfish

(Ictalurus punctatus)

Bluegill

(Lepomis macrochirus)

Largemouth bass 

(Micropterus salmoides)

Walleye

(Stizostedion vitreum)

Manchester NFH1 , Iowa 

Manchester NFH, Iowa 

Osceola SFH2 , Wis.

Jordan River NFH, Mich. 

and St. Croix Falls SFH, 

Wis.

Garrison Dam NFH, N.D. and 

Gavins Point NFH, S.D.

Fairport NFH, Iowa 

Lake Mills NFH, Wis. 

Genoa NFH, Wis. 

Garrison Dam NFH, N.D.

1 National Fish Hatchery

2 State Fish Hatchery

At least 10 of the 1- to 3-inch fish served as 

controls. The bioassays with the 3- to 5-inch 

and 6- to 9-inch fish were conducted in polyethylene tanks containing 45 liters of aerated 

solution. Five concentrations were tested 

against the 9-inch fish and 10 fish served as 

controls.

Waters of different hardnesses and pH were 

prepared by adding greater or less amounts of 

reconstituting salts to deionized water (table 2). 

Temperatures of 7°, 12°, 17°, and 22° C. were 

maintained by placing the bioassay vessels in 

thermostatically controlled water baths. All 

temperatures are reported in Celsius.

Aliquots of Eastman-grade methylpentynol, 

purchased from Eastman Organic Chemicals, 

were pipetted into the bioassays to yield the 

desired concentrations.

The data on survival and mortality were 

recorded at 24, 48, and 96 hours and were 

analyzed according to the methods of Litchfield 

and Wilcoxon (1949) to determine LCSO's, 

variations, slope functions, and 95-percent 

confidence intervals.

RESULTS

Species and Sizes of Fish

The LCSO's of methylpentynol range from 

660 to 1,890 p.p.m. in 96-hour bioassays for 

all species tested (table 3). Channel catfish, 2 

and 4 inches long, are the most resistant species while small lake trout are the most sensitive.

Larger brown trout and lake trout are more 

resistant to the lethal effects of methylpentynol than the 2-inch ones. This is apparent 

with brown trout and lake trout at all observation periods, and with one lot of rainbow 

trout at 96 hours. The medium sized brown 

trout and lake trout tolerate concentrations 

which approximate those tolerated by the 

larger individuals. LCSO's range from 1,060 

to 1,160 p.p.m. in 96 hours for 3- to 7-inch 

brown trout and lake trout.

Three- and 4-inch brook trout responded 

uniformly to methylpentynol with 96-hour 

LCSO's of 1,200and 1,280 p.p.m. respectively. 

However, the 6-inch fish appear more sensitive in the 96-hour bioassay. This may be 

explained by the fact that they contracted furunculosis just prior to the bioassays. Unfortunately, the disease was not diagnosed until 

after the tests.

Methylpentynol acted slowly at the concentrations tested, and little or no mortality occurred within 3 hours, even at concentrations

TABLE 2.--Water qualities obtained with different amounts of reconstituting salts in deionized water

Classification 

of

water

Soft .....................

^ h Q n r\ o "prl

c

NaHC03

12

4$

192

Salt added

CaS04

7.5

30.0

120.0

in mg./l.

MgS04

7.5

30.0

120.0

KC1

0.5

2.0

8.0

pH

range

6.4-6.8

7.2-7.6

7.6-8.0

Concentration

Total hardness

10-13

4-0-4-8

160-180

as p.p.m. CaC03

Total alkalinity

10-13

30-35

110-120

1 Standard reconstituted water used in routine bioassay.
Leif L. Marking: Toxicity of Methylpentynol to Selected Fishes 5

TABLE 3.--Toxicity of methylpentynol to nine species of fish at 12 C.

Species

Do.....................

Do.....................

Do.....................

Do.....................

Do.....................

Do.....................

Do.....................

Do.....................

Do.....................

Do.....................

Do.....................

Do.....................

Walleye ..................

Average ApproJ 

weight (grams) length

1.9 2 

1.6 2 

23.0 6 

2.6 2 

14.3 4 

27.0 6 

12.5 3 

20.0 4 

37.5 6 

2.0 2 

5.6 3 

35.0 7 

1.8 2 

1.9 2 

5.2 4 

1.3 2 

2.8 3 

0.5 1 

5.2 4 

63.0 7 

0.7 2

LC50 (p. p.m.) and 95-percent confidence interval at cimate \r r '

inches) 24 hourg

1,220 

1,151-1,294

1,340 

1,276-1,407

1,300 

1,204-1,404

820 

745-902

1,090 

1,048-1,134

1,130 

1,100-1,158

1,300 

1,250-1,352

1,375 

1,317-1,430

1,210 

1,142-1,283

900 

849-954

1,280 

1,143-1,434

1,220 

1,140-1,305

1,050 

1,012-1,077

1,770 

1,702-1,841

1,890 

1,817-1,966

1,390 

1,337-1,446

1,370 

1,317-1,425

1,250 

1,220-1,282

1,270 

1,233-1,308

1,400 

1,321-1,484

1,225 

1,156-1,298

48 hours

1,150 

1,095-1,208

1,280 

1,219-1,344

1,290 

1,217-1,367

750 

714-786

1,085 

1,033-1,139

1,100 

1,028-1,177

1,270 

1,221-1,321

1,300 

1,250-1,352

1,175 

1,108-1,246

860 

789-937

1,230 

1,108-1,365

1,200 

1,132-1,272

1,000 

943-1,060

1,770 

1,702-1,841

1,890 

1,817-1,966

1,340 

1,301-1,380

1,350 

1,320-1,382

1,250 

1,202-1,282

1,185 

1,129-1,244

1,300 

1,250-1,352

1,160 

1,048-1,288

96 hours

870 

753-1,005

1,250 

1,214-1,288

1,260 

1,223-1,298

680 

636-728

1,060 

1,010-1,113

1,100 

1,038-1,166

1,200 

1,132-1,272

1,280 

1,231-1,331

1,100 

1,028-1,177

660 

584-746

1,160 

1,084-1,241

1,160 

1,094-1,230

<900

1,700 

1,604-1,802

1,890 

1,817-1,966

1,340 

1,301-1,380

1,260 

1,189-1,336

1,170 

1,114-1,228

1,100 

1,028-1,177

1,250 

1,190-1,312

1,140 

1,027-1,265

substantially higher than those required to 

kill fish at 24 hours. Little additional mortality occurred among any species after 24 

hours, except the small rainbow trout, brown 

trout, and lake trout. In fact, the LCSO's are 

identical, or nearly identical at 24, 48, and 96 

hours for some species.

Northern pike appear the most sensitive 

among the warmwater species. The young pike 

require a large supply of food and become 

predacious in the bioassay since no food is 

available. Also they become weak when not fed 

for 96 hours and a complete statistical evaluation could not be calculated at that time.
Investigations in Fish Control 30: Bureau of Sport Fisheries and Wildlife

TABLE 4.--Toxicity of methylpentynol to rainbow trout and bluegills at different temperatures

Species

Do...............

Do...............

Do

Temperature

(°c.)

7 

12 

17 

12 

17

LC50 (p. p.m.) and 95-percent confidence interval at

24 hours

1,450 

1,343-1,566

1,340 

1,276-1,407

1,390 

1,337-1,446

1,120 

1,040-1,198

48 hours

1,330 

1,255-1,410

1,280 

1,219-1,344

1,340 

1,301-1,380

1,070 

1,009-1,334

96 hours

1,330 

1,255-1,410

1,250 

1,214-1,288

930

845-1,023

1,340 

1,301-1,380

1,030 

928-1,143

Effects of Temperature

Methylpentynol is more toxic to 1.6- inch 

rainbow trout and 1.3-inch bluegills at the 

higher temperatures in 24- to 96-hour bioassays (table 4). The 96-hour LC50 for rainbow 

trout at 7° C. is 1,330 p.p.m. whereas at 

17° C. the value drops to 930 p.p.m. Although 

bluegills are less sensitive, the toxicity of the 

drug increases about 20 percent with an increase in temperatures from 12° to 17° C. 

The LCSO's for bluegills are 1,340 and 1,030 

p.p.m. at 12° and 17° C. respectively at 96 

hours. Little additional mortality of either 

species occurred after 24 hours and LCSO's 

are fairly consistent throughout the bioassay.

Effects of Water Quality

Methylpentynol appears equally toxic to 

1.9-inch rainbow trout in water containing 

about 11, 44, and 170 p.p.m. of total hardness 

at 24 and 48 hours and appears only slightly 

more toxic in the harder water at 96 hours 

(table 5). The difference appears insignificant

TABLE 5. Toxicity of methylpentynol to rainbow trout in 

selected water qualities1 at 12° C.

Water 

hardness1

Soft.....

Standard.

Medium. . .

LC50(p.p.m.) and 95-percent confidence interval at

24 hours

1,260 

1,202-1,320

1,230 

1,157-1,308

1,210 

1,163-1,258

48 hours

1,200 

1,135-1,268

1,190 

1,127-1,256

1,200 

1,138-1,265

96 hours

920 

821-1,018

980 

905-1,060

780 

603-1,009

1 Water quality described in table 2.

in soft and standard water hardness at all observation periods. The LCSO's ranged from 

780 to 920 in the three water hardnesses at 

96 hours.

DISCUSSION

Rainbow trout and bluegills are more sensitive to the toxic effects of methylpentynol at 

higher temperatures. This corresponds with 

efficacy trials of Howland and Schoettger 

(1969) in which higher temperatures stimulate 

the metabolic activity and the drug is assimilated much faster.

Anesthesia is induced by 1,500 to 8,000 p.p.m. 

of methylpentynol (Howland and Schoettger, 

1969). These concentrations exceed LCSO's 

for 24- to 96-hour bioassays, but the exposure 

time is only 4 to 57 minutes for effective 

anesthesia.

Parkhurst and Smith (1957) exposed rainbow 

trout to 2,400 p.p.m. of methylpentynol. Undoubtedly this concentration would become 

toxic to the trout in longer exposures.

CONCLUSIONS

The 96-hour LCSO's of methylpentynol to 

fish range from 660 to 1,890 p.p.m. Higher 

concentrations are necessary to produce effective anesthesia, but exposures are also 

much shorter.

Larger brown trout and lake trout are more 

resistant to the toxic effects of methylpentynol than smaller ones.
Leif L. Marking: Toxicity of Methylpentynol to Selected Fishes

The toxic effects of methylpentynol are 

manifest in 24 hours and little additional mortality occurs after this time.

Channel catfish are the most resistant and 

lake trout the most sensitive to methylpentynol.

Methylpentynol is more toxic to rainbow 

trout and bluegills at higher temperatures.

Changes in water hardnesses of approximately 12, 44, and 170 p.p.m. influence the 

toxicity of methylpentynol very little.

REFERENCES

Bayliff, William H., and Edward F. Klima.

1962. Live-box experiments with anchovetas, 

Cetengraulis mysticetus, in the Gulf of Panama. 

Inter-American Tropical Tuna Commission Bulletin, vol. 6, no. 8, p. 333-436.

Bell, Gordon R.

1964. A guide to the properties, characteristics, 

and uses of some general anaesthetics for fish. 

Fisheries Research Board of Canada, Bulletin 148. 4 p.

Carlson, Frank T.

1965. Susquehanna River shad study. Pennsylvania Angler, October, p. 1-17.

Fry, F. E. J., and K. S. Norris.

1962. The transporting of live fish, hi Georg 

Borgstrom, editor Fish as Food, vol. 2, 

chapter 17, p. 595-608. Academic Press, N.Y.

Hirsh, Harold L., and William H. Orsinger.

1952. Methylparafynol - a new hypnotic. Preliminary report on its therapeutic efficacy and 

toxicity. American Practitioner, vol. 3, no. 1, 

p. 23-26.

Howland, Robert M., and Richard A. Schoettger.

1969. Investigations in Fish Control: 29. The efficacy of methylpentynol as an anesthetic onfour 

salmonids. U.S. Bureau of Sport Fisheries and 

Wildlife.

Klontz, George W.

1964. Anesthesia of fishes. In Proceedings of the 

Symposium on Experimental Animal Anesthesiology, Brooks Air Force Base, December 14-16. 

13 p.

Lennon, Robert E.

1967. Clearance and registration of chemical tools 

for fisheries. The Progressive Fish-Culturist, 

vol. 29, no. 4, p. 187-193.

Lennon, Robert E., and Charles R. Walker.

1964. Investigations in Fish Control. 1. Laboratories and methods for screening fish-control 

chemicals. U.S. Bureau of Sport Fisheries and 

Wildlife. 15 p.

Litchfield, J. T., Jr., and F. Wilcoxon.

1949. A simplified method of evaluating doseeffect experiments. Journal of Pharmacology 

and Experimental Therapeutics, vol. 96, no. 2, 

p. 99-113.

Margdlin, S., F. Villani Perlman, and H. McGavack. 

1951. A new class of hypnotics: unsaturated 

carbinols. Science, vol. 114, p. 384-385.

McFai[land, William N.

1959. A study of the effects of anesthetics on the

behavior and physiology of fishes. Publication

of the Institute of Marine Science, University of

Texas, vol. 6, p. 23-55. 

19^60. The use of anesthetics for the handling and

the transport of fishes. California Fish and

Game, vol. 46, no. 4, p. 407-431.

Parkhurst, Z. E., and M. A. Smith.

19! 57. Various drugs as aids in spawning rainbow 

trout. The Progressive Fish-Culturist, vol. 19, 

no. 1, p. 39.

Sharpiess, Seth K.

1^65. Hypnotics and sedatives II. Miscellaneous 

agents. In The pharmacological basis of 

therapeutics, Third edition, edited by Louis S. 

Goodman and Alfred Gilman. The Macmillan 

Company, chapter 10, p. 129-142.

StecheT, Paul G., M. J. Finkel, O. H. Sigmund, and 

B. M. Szafranski, editors.

1^60. The Merck index of chemicals and drugs. 

Seventh edition. Merck & Co., Inc., 1,641 p.
INVESTIGATIONS IN FISH CONTROL

31. Annotated Bibliography on Methylpentynol

By Gerald E. Svendsen

UNITED STATES DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

Bureau of Sport Fisheries and Wildlife

Washington, D.C. February 1969
ANNOTATED BIBLIOGRAPHY ON METHYLPENTYNOL

By Gerald E. Svendsen, Biologist

Bureau of Sport Fisheries and Wildlife

Fish Control Laboratory, La Crosse, Wisconsin

Abstract. An annotated bibliography containing 26 selected references 

on the biochemistry, physiology, and methods of analysis of methylpentynol.

Experiments with methylpentynol as an 

anesthetic for four salmonids to describe its 

toxicity and efficacy began in 1964 at the Fish 

Control Laboratory, La Crosse, Wis. The U.S. 

Food and Drug Administration requires these 

data for clearance and labeling of drugs. 

During the study, a number of selected references on fishery uses of the drug, and on its 

biochemistry, physiology, and methods of 

analysis were annotated.

BIBLIOGRAPHY

Bayliff, William H., and Edward F. Klima. 

1962. Live-box experiments with anchovetas, Cetengraulis mysticetus, in the 

Gulf of Panama. Inter-American Tropical 

Tuna Commission Bulletin, vol. 6, No. 8, 

p. 333-436.

Four anesthetics quinaldine, MS-222, 

methylpentynol, and tertiary amyl alcohol 

were used to facilitate tagging operations. 

Quinaldine caused some mortalities and proved 

to be chemically unstable. Methylpentynol and 

tertiary amyl alcohol also killed some fish 

and acted too slowly for field use. The methylpentynol was used at a concentration of 6 milliliters per gallon. MS-222 is the most satisfactory of the chemicals tested, although there 

were some mortalities at the higher concentrations.

Bell, Gordon R.

1964. A guide to the properties, characteristics, and uses of some general anaesthetics for fish. Fisheries Research 

Board of Canada, Bulletin 148. 4 p.

The structural formulas, manufacturers, 

dosages, toxicities, and solubilities are presented for 11 chemicals used as fish anesthetics: carbon dioxide, chloral hydrate, 

chloretone, ether, methylpentynol, MS-222, 

phenoxyethanol, quinaldine, sodium amytol, 

tribromomethanol, and tertiary amyl alcohol. 

Methylpentynol is recommended at a dosage of 

1 to 2 milliliters per liter in transportation. 

Bell does not recommend it as an anesthetic 

for surgery because immobilized fish twitch 

when prodded or cut. Methylpentynol immobilizes fish slowly with occasional violent 

struggling, but recovery is rapid in fresh 

water.

Carlson, Frank T.

1965. Susquehanna River Shad study. Pennsylvania Angler, October, p. 1-7. 

Shad were transported in a solution containing 1 milliliter of methylpentynol per 

gallon of water. They were anesthetized in a 

15-gallon tub of river water containing 3 milliliters of methylpentynol per gallon.

Fry, F. E. J., and K. S. Norris.

1962. The transporting of live fish. In 

Georg Borgstrom, Editor Fish as Food, 

Vol. 2, Chap. 17, p. 595-608. Academic 

Press, N.Y.

The authors suggest methylpentynol for 

use in transporting live fish.

Hirsh, Harold L., and William H. Or singer. 

1952. Methylparafynol- a new hypnotic. 

Preliminary report on its therapeutic efficacy and toxicity. American Practioner, 

vol. 3, no. 1, p. 23-26.
Investigations in Fish Control 31: Bureau of Sport Fisheries and Wildlife

Patients received a 100 to 800 milligram 

dose of methylpentynol as a sedative with no 

after effects on blood pressure, pulse, respiration rate, blood and urine composition, 

electrocardiogram, or liver and kidney function. The authors considered methylpentynol a 

safe, nontoxic, efficient, rapid, and long lasting hypnotic drug in humans.

Howland, Robert M., and Richard A. 

Schoettger.

1969. Investigations in Fish Control: 

29. The efficacy of methylpentynol as an 

anesthetic on four salmonids. U.S. Bureau 

of Sport Fisheries and Wildlife. 

Methylpentynol was tested as an anesthetic 

against rainbow trout, brown trout, brook 

trout, and lake trout. Concentrations ranging 

from 1.5 to 8.0 parts per thousand produced 

anesthesia within 4 to 57 minutes respectively. 

They studied the effects of water temperature, water quality, and pH on the rate of 

anesthetization and found that only temperature had a measurable effect. The authors 

concluded that methypentynol is better suited 

as a sedative than 4s an anesthetic for salmonids, because fish under anesthesia are 

not completely immobilized.

Job, C. von.

1959. Die Beziehungen zwischen der starke 

der narkotischen wirkung und der thermodynamischen konzentration bei estern 

des methylpentinols. ArzneimittelForschung, vol. 9, no. 1, p. 14-22. 

The author investigated the effects of 

methylpentynol and some of its esters on the 

rat and on the isolated frog nerve. Action potentials of the isolated frog nerve are retarded 

and interrupted under the influence of methylpentynol. Methylpentynol blocks conduction of 

stimuli at a concentration of 5 grams per 

liter.

Kennedy, Walter A., and Edward Mar ley. 

1959. The electroencephalographic effects 

of methylpentynol. Electroencephalography and Clinical Neurophysiology, 

vol. 2, no. 1, p. 59-64. 

The authors discuss several aspects of the 

drug in clinical work, and cite cases of overdosage and side effects from methylpentynol. 

They found a correlation between the degree

of electroencephalographic abnormalities and 

the amount of physical disturbance produced 

in patients given 0.5 gram of methylpentynol 

orally for 5 days.

Klontz, George W.

1964. Anesthesia of fishes. In Proceedings 

of the Symposium on Experimental Animal 

Anesthesiology. Brooks Air Force Base, 

December 14-16. 13 p. 

Techniques for anesthetizing fish and a 

brief description are given for 15 agents: 

carbon dioxide, electricity, diethyl ether, 

secobarbital sodium, amobarbitol sodium, 

urethane, chloral hydrate, tertiaryamyl 

alcohol, tribromoethanol, chlorobutanol, 

2-phenoxyethanol, 4-styrylpyridine, methylpentynol, quinaldine, and MS-222. Concentrations of 0.5 to 0.9 milliliter per liter of methylpentynol are suggested to induce anesthesia 

within 2 to 3 minutes. Maintenance of anesthesia is considered fair, and the recovery of 

fish in fresh water occurs in 5 to 20 minutes. 

The author also rated the maintenance of deep 

anesthesia as fair because fish seem to go 

into respiratory arrest. He considered the 

odor of methylpentynol quite disagreeable.

Lasagna, Louis.

1954. A comparison of hypnotic agents. 

The Journal of Pharmacology and Experimental Therapeutics, vol. Ill, p. 9-20. 

The author used chloral hydrate, pentobarbital sodium, methylpentynol, and a placebo 

to determine which doses are most useful for 

inducing prolonged sleep in man. A dosage of 

0.5 to 1.0 gram of methylpentynol induced 

sleep that was undistinguishable from that of 

the placebo.

Leal, Aluiso Marques, and Maria Helena 

Diniz.

1956. Assay of methylpentynol in galenic 

preparations. Revista Portuguesa de 

Farmacia, vol. 6, p. 14-17. 

Two titrimetric methods for the assay 

of methylpentynol in body fluids are described.

Margolin, S., P. Perlman, F. Villani, and 

T. H. McGavack.

1951. A new class of hypnotics: unsaturated 

carbinols. Science, vol. 114, p. 384-385.
Gerald E. Svendsen: Annotated Bibliography on Methylpentynol

Methylpentynol was studied for use as a 

clinical hypnotic. The LC50 for mice, rats, 

and guinea pigs is 600 to 900 mg./kg. (milligrams per kilogram). The animals died in 

coma. Two hundred to 300 mg./kg. had no effect 

on mice, rats, and dogs. One half to 4.6 percent 

of a 200-mg./kg. dose fed to dogs was excreted 

in the urine within 24 hours. Ten minutes after 

an intravenous administration of 200 mg./kg. 

to dogs, 20 percent of the dose is found in the 

blood, but none is present after 2 hours. 

Tweny percent of an 800-mg./kg. dose is 

found in the muscle and liver tissues taken 

from rats which are still under hypnosis. No 

residues were found in these tissues after the 

effects of anesthesia wore off. Methylpentynol 

was not metabolized by whole blood of dogs or 

rats but it was metabolized by slices of kidney, 

liver, or brain.

Marking, Leif L.

1969. Investigations in Fish Control: 30. 

The toxicity of methylpentynol to selected 

fishes. U.S. Bureau of Sport Fisheries 

and Wildlife.

Toxicity of methylpentynol to rainbow 

trout, brown trout, brook trout, lake trout, 

northern pike, channel catfish, bluegills, 

largemouth bass, and walleyes of various 

sizes ranged from the 96-hour LC S o value of 

660 p.p.m. (parts per million), for the more 

sensitive lake trout to 1,890 p.p.m. for channel catfish at 12° C. Larger rainbow, brook, 

and lake trout were considerably more resistant than smaller ones. Rainbow trout and 

bluegills are more sensitive to methylpentynol in warmer temperatures. Total hardnesses 

of 10.0 to 170.0 p.p.m. produced similar results in the static bioassays. Methylpentynol 

is much less toxic than other anesthetics 

tested in the 24-, 48-, and 96-hour static 

bioassays at selected temperatures and water 

qualities.

Mar ley, E.

1959. Pharmacology of methylpentynol and 

methylpentynol carbamate. British Journal of Pharmacology, vol. 14, p. 284-306. 

Methylpentynol and methylpentynol carbamate are depressants of monosynaptic and 

polysynaptic reflexes in cats, frogs, rabbits, 

and guinea pigs. Small doses exerted weak 

ganglionic andneuromuscular blocking actions,

increased aortic blood flow, diminished systolic amplitude, increased coronary flow, and 

stimulated respiration. Large doses depressed 

respiration.

Mar ley, E., and W. D. M. Paton.

1959. The effect of methylpentynol and 

methylpentynol carbamate on the perfused 

superior cervical ganglion of the cat. 

British Journal of Pharmacology, vol. 14, 

p. 303-312.

The output of acetylcholine in the perfused 

cervical ganglion is depressed by dosages of 

1 to 5 milligrams of the drugs.

Marley, E., and J. R. Vane.

1958. The distribution of methylpentynol 

and methylpentynol carbamate in tissues 

and body fluids of cats. British Journal of 

Pharmacology, vol. 13, p. 364-371. 

The authors present a modified titrimetric 

method for estimating methylpentynol in 

amounts as small as 0.1 milligram. They 

found no difference between plasma concentrations and whole blood concentrations of 

methylpentynol 10 minutes after injection. 

They concluded that the drug has free access 

to all parts of the body, and general anesthesia 

does not inhibit its metabolism and excretion. 

It enters cells easily, where it tends to accumulate.

Marley, Edward.

1958. Susceptibility to methylpentynol and 

methylpentynol carbamate. British Medical Journal, Medical Memoranda, August 23, p. 493.

He compared the toxicities of methylpentynol and methylpentynol carbamate in 

man. Methylpentynol at 0.5 gram per day for 

5 days causes many toxic effects in man.

McFarland, William N.

1959. A study of the effects of anesthetics 

on the behavior and physiology of fishes. 

Publications of the Institute of Marine 

Science, University of Texas, vol. 6, 

p. 23-55.

The anesthetic effects of 21 chemicals on 

Fundulus parvipinnis, Gambusia affinis, 

Paralabrax alathratus, and Girella nigricans 

were investigated. The effects on behavioral 

patterns are observed in four major stages: 

sedation, loss of equilibrium, loss of reflex,
Investigations in Fish Control 31: Bureau of Sport Fisheries and Wildlife

and medullary collapse. These stages are 

compared to the sequence of anesthesia described for higher vertebrates. Narcotic 

potencies are correlated with molecular 

weight of the drugs. Methylpentynol is rated 

highly potent.

McFarland, William N.

1960. The use of anesthetics for the handling and the transport of fishes. California Fish and Game, vol. 46, no. 4, 

p. 407-431.

The author suggested that MS-222, tertiary 

amyl alcohol and methylpentynol are beneficial for inducting deep anesthesia because the 

drugs act quickly and the fish recover rapidly. 

Recovery is complete, provided the respiratory movements have not ceased for more than 

a few minutes. A concentration of 1.5 to 2.0 

milliliters per gallon of methylpentynol is considered desirable for transporting marine and 

freshwater fishes. Methylpentynol lowers 

metabolic rates and therefore increases load 

capacity. He suggests that fishes should be ' 

pretreated in the anesthetic to reduce metabolic rates prior to loading and transportation.

Nicholls, J. G., and J. P. Quilliam.

1956. The mechanism of action of paraldehyde and methylpentynol on neuromuscular transmission in the frog. British 

Journal of Pharmacology, vol. 11, p. 1 SI155. 

Paraldehyde and methylpentynol block

neuromuscular transmission by decreasing

the secretion of acetyl cholinesterase at the

synapse in the frog.

Norris, Kenneth S., Frank Brocato, Frank 

Calandrino and William N. McFarland. 

1960. A survey of fish transportation methods and equipment. California Fish and 

Game, vol. 46, no. 1, p. 5-33. 

Methylpentynol is suggested as a useful 

anesthetic in fish transportation.

Parkhurst, Z. E., and M. A. Smith.

1957. Various drugs as aids in spawning 

rainbow trout. The Progressive FishCulturist, vol. 19, no. 1, p. 39. 

A methylpentynol concentration of 2,400 

p.p.m. caused sluggishness and relaxation in

rainbow trout. The trout are ready for spawning in 3.5 minutes at a water temperature of 

43° F. Somewhat longer exposures are not 

harmful. Trout remained in good condition 75 

days after spawning. There was an 84.1 percent hatch from those fish spawned with 

drugs, and an 84.0 percent hatch from controls.

Pepeu, Giancarlo, and Nicholas J. Giarman. 

1960. Effect of methylpentynol on acetylcholine in the rats brain. Nature, vol.

186, p. 638.

The authors found that methylpentynol did 

not interfere with the synthesis of acetylcholine in the rat brain, nor did it inhibit 

cholinesterase activity. Male rats were given 

intraperitoneal injections of methylpentynol in 

a dosage varying from 200 to 500 milligrams/ 

kilogram.

Perlman, Preston L., and Carol Johnson.

1952. The metabolism of Dormison (3- 

methyl-pentyne-ol-3, methyl-parafynol) 

and methods for the estimation of 

Dormison in biological materials. Journal 

of the American Pharmaceutical Association, vol. 41, no. 1, p. 13-16. 

The authors described a tritrimetric method 

for estimating methylpentynol in biological 

fluids and tissue. They studied the metabolism 

of methylpentynol in dogs. Methylpentynol is 

metabolized by destruction of the ethinyl 

group, which metabolizes quite rapidly. This 

is revealed by the rapid decline in the blood 

level of methylpentynol and the slow level of 

elimination of the chemical in the urine, and 

in vitro by the disappearance of the ethinyl 

group by metabolizing rat tissues. They found 

no evidence of storage or accumulation of the 

drug in tissues.

Perlman, Preston L., David Sutter, and 

Carol B. Johnson.

1953. Further studies on the metabolic deposition of Dormison (3-methyl-1-pentyn3-ol) in dogs and man. Journal of the 

American Pharmaceutical Association, 

vol. 42, no. 2, p. 750-753. 

Dogs eliminated 17-27 percent of the administered methylpentynol conjugated with 

glucuronic acid; 1 percent unchanged in the 

urine, and none by way of the lungs or feces.
Gerald E. Svendsen: Annotated Bibliography on Methylpentynol

In man, up to 10 percent is eliminated unchanged, and 17-27 percent as conjugates of 

glucuronic acid. The peak levels for elimination of the drug are reached within 48 hours.

Quilliam, J. P.

1959. Paraldehyde and methylpentynol and 

ganglionic transmission. British Journal 

of Pharmacology, vol. 14, p. 277-283. 

Paraldehyde and methylpentynol block 

transmission of the impulse at preganglionic 

nerve terminals in cats. The author suggests 

that this is caused by a decrease in the secretion of acetycholine from the preganglionic 

nerve terminals.

Schafferzich, S., and Beverly J. Brown. 

1952. Anticonvulsant activity and toxicity 

of methylparafynol (Dormison) and some 

other alcohols. Science, vol. 116, p. 663. 

The authors used phenobarbitol, 2-methyl2-propanol, 2-methyl-2,4-pentamediol, 3- 

pentanol, 2-methyl-2-butanol, and methylpentynol as an anticonvulsant in treatment of 

epilepsy. Rats were not effected by 0.17 

percent methylpentynol in their drinking water

for 4 months. The LDS o of methylpentynol to 

rats is 300 to 900 milligrams per kilogram. 

They concluded that methylpentynol is the 

least safe of those chemicals studied.

Sheldon, J. M.

1965. Plastic bag transport of salmon and 

steelhead by air and car. The Progressive 

Fish-Culturist, vol. 27, no. 2, p. 86. 

The author used methylpentynol, 0.67 milliliter per gallon of water, as a sedative to 

transport salmon and steelhead in plastic bags. 

Three milliliters of 10 percent Dow-Corning 

Antifoam emulsion was added to prevent excessive foaming.

Smith, J. N., and R. T. Williams.

1954. The metabolism of aliphatic alcohols. 

The glucuronic acid conjugation of chlorinated and some unsaturated alcohols. 

Biochemistry Journal, vol. 56, p. 618-621. 

They studied the conjugation of glucuronic 

acid with a number of chlorinated and other 

aliphatic alcohols in the rabbit. About 50 percent of the methylpentynol is conjugated with 

glucuronic acid and excreted in the urine.

U.S. GOVERNMENT PRINTING OFFICE : 1969 O - 338-452
(Reports 18 through 21 are in one cover.)

18. Toxicity of 22 Therapeutic Compounds to Six Fishes, by Wayne A. Willford. 1967. 10 p.

19. Toxicity of Bayer 73 to Fish, by Leif L. Marking and James W. Hogan. 1967. 13 p.

20. Toxicity of Dimethyl Sulfoxide (DMSO) to Fish, by Wayne A. Willford. 1967. 8 p.

21. Labor-Saving Devices for Bioassy Laboratories, by Robert J. Hesselberg and Ralph M. 

Burress. 1967. 8 p.

(Reports 22 through 24 are in one cover.)

22. Efficacy of Quinaldine as an Anesthetic for Seven Species of Fish, by Richard A. Schoettger 

and Arnold M. Julin. 1969. 10 p.

23. Toxicity of Quinaldine to Selected Fishes, by Leif L. Marking. 1969. 10 p.

24. Quinaldine as an Anesthetic for Brook Trout, Lake Trout, and Atlantic Salmon, by 

David O. Locke. 1969. 5 p.

(Reports 25 through 28 are in one cover.)

25. Field Trials of Antimycin as a Selective Toxicant in Channel Catfish Ponds, by Ralph M. 

Burress and Charles W. Luhning. 1969. 12 p.

26. Laboratory Studies on Antimycin A as a Fish Toxicant, by Bernard L. Berger, 

Robert E. Lennon, and James W. Hogan. 1969. 19 p.

27. Field Trials of Antimycin A as a Fish Toxicant, by Philip A. Gilderhus and Robert E. 

Lennon. 1969. 21 p.

28. Use of Antimycin for Selective Thinning of Sunfish Populations in Ponds, by Ralph M. 

Burress and Charles W. Luhning. 1969. 10 p.
As the Nation's principal conservation agency, the Department of 

the Interior has basic responsibilities for water, fish, wildlife, 

mineral, land, park, and recreational resources. Indian and Territorial affairs are other major concerns of this department of 

natural resources.

The Department works to assure the wisest choice in managing 

all our resources so that each shall make its full contribution to a 

better United States now and in the future.

UNITED STATES 

DEPARTMENT OF THE INTERIOR

FISH AND WILDLIFE SERVICE

BUREAU OF SPORT FISHERIES AND WILDLIFE 

WASHINGTON, D-C. 20240