Psychological Reports, 1975, 36, 979-985.

@ Psycho!ogical Reports 1975

SURVIVAL TIME A N D WEIGHT LOSS IN GOLDFISH (CARASSIUS AURATUS)' ALLEN H . WOLACH, MAUREEN A. MC HALE,? CLARA S. FITZPATRICK, A N D REED DUNLAP Illiaois Inrtitute of Technology Summary.-Goldfish in Experiment 1 were placed on terminal deprivation when they reached 2, 3, 4, or 16 mo. Fish that were 4-mo.-old showed the greatest median survival time ( 2 mo.). Large fish lost a smaller percentage of their weight before death than small fish. Fish, unlike mammals, did not die when they lost a fixed percentage of their predeprivation weighr. A second experiment was performed to assess recovery from deprivation. Feeding was reinstated for some of the fish after different numbers of days of deprivacion (2, 28, 44, or 64 days). Fish that survived until feeding was reinstated recovered from deprivation.

Studies with mammals on terminal deprivation have shown that they die after losing a fixed percentage of their body weight (e.g., Campbell, Teghtsoonian, & Williams, 1961). Campbell, et al. have shown that rats on terminal deprivation die when they lose 43% of their predeprivation weight. The finding that female rats die before male racs and younger racs die before older rats is not inconsistent with the observation that rats die when they lose 43% of their predeprivation weighr. For example, younger (lighter) rats take less time to lose 43% of their weight than older (heavier) racs. The present study includes an investigation of terminal deprivacion conditions in a cold-blooded species. The study was intended to show whether goldfish (Carassias awatus), like mammals, die when they lose a fixed percentage of their body weight or if factors such as age are more directly correlated with time to death. When rats are used as subjects in instrumental studies, behavior is more directly correlated with weight loss as opposed to deprivation time, consumrnatory activity, or incentive (e.g., Bolles & Petrinovich, 1956; Treichler & Hall, 1962). The behavioral evidence coupled with the finding that rats die after losing a fixed percentage of their body weight suggests that equating percentage weight loss is one of the best ways to motivate mammals in learning studies. Terminal-deprivation data for fish can be useful for determining deprivation procedures for fish in learning studies. For example, if fish die when they lose a fixed percentage of their weight and their instrumental behavior is correlated with weight loss, measures of percentage weight loss would gain support as useful indicators of motivation in goldfish. Conversely, if percentage weight loss is not related to time of death for fish, other indices of motivation gain credence, e.g., hours of deprivacion. 'Requests for reprints should be sent to Allen H. Wolach, Department of Psychology, Illinois Institute of Technology, Chicago, Illinois 60616. Wow at Northwestern State University of Louisiana, Natchitoches, Louisiana 71457.

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EXPERIMENT1 Method Subjects.--Common goldfish (Carassius auratus) were obtained from Grassy Forks Fisheries, Martinsville, Indiana, within 2 mo. after the spawning season. W h e n the fish arrived at the laboratory, they were randomly assigned to groups as required. Deprivation for fish started within 1 to 4 mo. after their arrival at the laboratory. There were 2 8 fish that started deprivation when they were 2-mo.-old, 33 fish that started deprivation when they were 3-mo.-old, 28 fish that started deprivation when they were 4-mo.-old, 2 3 fish that started deprivation when they were 13-mo.-old, and 27 fish that started deprivation when they were 16-mo.-old. All fish were fed in their individual containers for at least 2 weeks prior to deprivation. T h e fish were fed during a Yz-hr. period at the same time every day. Small quantities of food (Longlife Freeze Dried Tubifex Worms and Longlife Freeze Dried Brine Shrimp from Sternco Industries, Harrison, New Jersey) were repeatedly placed in each container as the fish consumed them until the fish failed to eat any more. Uneaten food was removed from the container a t the end of the daily feeding period. T h e feeding procedure guaranteed that a fish's water would not get polluted by large quantities of uneaten food. Fish on deprivation received no food. Each group of fish o n deprivation was paired with a comparable sized control group maintained with food. A given control group was within 2 fish of the experimental group with which it was paired; e.g., the control group for the 28 fish that started deprivation at 2 mo. had 2 9 fish. The control fish were maintained with the feeding conditions described above until the last experimental fish had died. Except for feeding, the control fish experienced conditions identical to those for deprived fish. Vircually no control fish died during the study (one 3-mo. control fish and one 16-mo. control fish died). The control fish were used to determine if deaths for food deprived fish were related to deprivation rather than other factors such as disease. Since virtually none of the control fish died (and all experimental fish died) comparisons between control deaths and experimental deaths are not necessary. Older ( 1 6 and 1 3 mo.) control fish maintained their weights, while younger control fish ( 2 , 3, and 4 mo.) gained approximately .3 gm. per month. Apparatus and procedure.-The fish were maintained in individual plastic containers (29.0 x 18.5 x 11.0 cm.) that held 3.8 liters of dechlorinated water. All goldfish were weighed every fourth day with a beam balance. A container of water (15.0 cm. in diameter and 8.0 un. high) was placed o n each pan of the balance. A fish was brought to the scales in a porous net and placed in one of the containers. T h e water in a home container was changed while the fish was weighed.

Results and Discussion Days to death.--Goldfish in the present study were maintained under conditions that are fairly representative of maintenance procedures for fish in learning studies (individual containers with no filtration system). It can be argued that feeding fish for 1/2 hr. every day does not keep them at ad lib. weight. However, most studies with fish have used one feeding per day after the fish were individually housed. Continuous access to food creates a water-pollution problem that requires filtration for each fish container. Since fish in the present study were individually housed and individually fed before deprivation was initiated, it is possible that age of fish interacted with potential weight gain and time to death through social facilitation, e.g., young fish may have eaten more if

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they were not individually housed before deprivation was initiated. Again, the procedure used (individual housing) was representative of conditions that goldfish typically encounter in learning studies. Although it would have been interesting to investigate terminal deprivation conditions for fish that lived in individual containers for nearly 1 yr. before deprivation was initiated, such conditions are not typical of predeprivation conditions for fish in learning studies. The placement of fish in individual containers soon after birth would not guarantee uniform or representative populations at each age level. First, home-container conditions could interact with age and site to produce more advantageous conditions for fish of different ages and sizes. Secondly, older fish ( 16 mo.) that are individually housed soon after birth experience an environment that is very different from the environment which older fish experience when they live with other fish in breeding ponds for a large portion of their lives. The comparisons for fish deprived at 2, 3, and 4 mo, can be considered as a distinct experiment relative to the comparisons for fish deprived at 13 or 16 rno. The younger fish ( 2 , 3, and 4 mo.) were subjected to laboratory conditions (individual housing) at an early age and placed on deprivation when they reached an appropriate age. The older fish ( 1 3 or 16 mo.) lived in Grassy Forks Fisheries' four outdoor ponds for approximately one year before they were brought to the laboratory for the deprivation study. Although the preexperimental conditions for younger fish were better controlled than the preexperimental conditions for older fish, the conditions for older fish were typical of environmental conditions for goldfish that are delivered to laboratories for experimentation. It should be noted that goldfish delivered by suppliers for learning experiments are older than 4 mo. (usually over 1 yr.) when they arrive at the laboratory. Younger fish do not survive transportation from the pond to a local supplier (or directly to a laboratory). The younger goldfish in the present study were transported to the laboratory in a temperature controlled van. The fish were transported with a small number of fish per container to minimize trauma during transportation. If one assumes thac pre-experimental living conditions led to different populations of fish for older ( 13 and 16 mo.) and younger (2, 3, and 4 mo.) fish, data from older and younger fish can be considered separately. The analyses described below make it possible to compare older and younger fish separately or as a totality. Fig. 1 shows the relationship between days of deprivation and number of deaths for goldfish of different ages. Campbell, et al. (1961) have shown thac rats (100-days-old) on terminal deprivation averaged 12 days before they died. Fig. 1 shows chat fish of all ages typically take much longer to die than rats. Four-mo.-old goldfish averaged 2 mo. before they died. A Kruskal-Wallis one-way analysis of variance showed that the five groups

A. H. WOLACH. ET AL.

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2 MONM FiSH

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m

7

3 MONTH FISH LL

3

4

1-4

2W4 41.49 61-64 81-84 1-4 Z l a 4l-44 6?64 FOUR DAY BLOCKS OF DEPRIVATION

FIG. 1. Number of days until death for 2-, 3-, 4-, 13-, and 16-mo.-old goldfish. The arrow above each panel indicates the median number of days until death.

(2, 3, 4, 13, and 16 mo.) had significantly different average survival times = 94.31, p < .001). Fig. 1 indicates that the younger fish increased their survival time from 2 to 4 mo. A Kruskal-Wallis one-way analysis of variance ( 2 vs 3 vs 4 mo.: H 2 = 52.14, p < ,001) indicates that survival time increased as age before deprivation increased from 2 to 4 mo. The older fish ( 1 3 and 16 mo. before deprivation) had shorter median survival times than the 2- or 4-mo. fish and produced a more varied distribution of survival times. A MannWhitney U test indicated similar survival times for older 13- versus 16-mo. fish ( p .05). Percentage weight loss.-Panel 1 of Fig. 2 shows median percentage weight loss for 3-, 4-, and 16-m0.-old fish. Although graphs are not presented for the 2- and 13-mo.-old fish, the 2- and 13-mo. fish produced data that support the data obtained with 3-, 4-, and 16-mo.-old fish (the 3-, 4-, and 16-1110. fish were weighed with a more accurate scale), i.e., 2-mo.-old fish died when they lost slightly under 50% of their prefeeding weighc and 13-mo.-old fish died when they lost less than 25% of their weight. Percentage weight loss relative to the fish's predeprivation weight was calculated for each fish in each 4-day block. The median for a given block in Panel 1 of Fig. 2 contains data only for fish which were still alive. The curve for a given age is discontinued after half the fish died. Panel 2 of Fig. 2 shows median percentage weighc loss taken from each fish a given number of days before death. A given fish was weighed only once in a 4-day block to ensure the fish was not traumatized. Panel 1 of Fig. 2 indicates that by the time half the 3- and 4-mo.-old fish had died the median weight loss for the remaining fish was approximately 40% of their predeprivation weight. When half the 16-mo.-old fish had died, the (H4


.05). Panels 1 and 2 of Fig. 2 would indicate similar differences in percentage weight loss for fish in a given age category if mean weight loss for fish of a given age (rather than the median described above) is plotted. Percentage weight loss for fish of different weights.-Panels 3 and 4 of Fig. 2 show that the weight of fish of a given age determines percentage weight loss. Data in Panels 3 and 4 of Fig. 2 are from the 27 fish which started deprivation when they were 16-mo.-old. Percentage weight Loss is plotted separately for the 13 light fish (1.5 through 3.0 gm.), the 4 medium fish (4.5 through 7.0 gm.), and the 10 moderately heavy fish (7.5 through 14.5 gm.). Panels 3 and 4 in Fig. 2 indicate chat lighc fish lost 40 to 50% of their body weight before death, while medium we~ghcand moderately heavy fish lost only 15 to 25% of their body weight.

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A Kruskal-Wallis one-way analysis of variance was performed on the data for the three weight ranges. The data for a given weight range consisted of a percentage weight loss for each fish in the weight range. The percentage weight loss for a given fish was from the four-day period before its death. The KcuskalWallis one-way analysis of variance showed a different percentage weight loss for the three weight categories (1.5 through 3.0 gm., 4.5 through 7.0 gm., and 7.5 through 14.5 gm.; H z = 16.91, p < ,001). Follow up a posterzori tests (see Kirk, 1968, pp. 497-498) showed that light (1.5 through 3.0 gm.) fish lost a greater percentage of their weight than heavy (7.5 through 14.5 gm.) fish (d(8.15) = 10.99, p < .05). Light (1.5 through 3.0 gm.) versus medium (4.5 through 7.0 gm.), and medium ( p > .05) versus heavy (7.5 through 14.5 gm.) comparisons did not yield significant differences ( p > .05). The percentage weight loss curve for the light 16-mo. fish is very similar to the percentage weight loss curve for 3- and 4-mo. fish (Panel 1 of Fig. 2 ) . The data for the 3- and 4-mo.-old fish cannot be divided into data for fish of different weights because these fish had a restricted weight range (.5 to 3.0 gm.) before deprivation started. Panels 3 and 4 of Fig. 2 would look very similar if data from younger fish would be included in the three weight categories. The data show that weight loss at death for fish is dependent on the weighc of the fish before deprivation is started. Panels 3 and 4 of Fig. 2 would indicate similar differences in percentage weight loss for fish in a given weight category if mean weight loss for fish of a given weight (rather than the median measure described above) is plotted. Results from the present study are very different from the Campbell, et al. (1961) results that show rats of varied ages and sizes die at 43% weight loss. The only difference in weight loss curves for small 16mo. fish and younger fish ( 1 to 4 mo.) of the same weight is the smaller number of days until death for older fish. This may merely reflect that small (light) older fish are not as hardy as younger fish of the same weight (many of the light younger fish would have become heavy fish as they macured) or larger fish of the same age. Whatever the merit of percentage weight loss as a deprivation criterion for rats, the present investigation argues against such a criterion for motivating goldfish in learning studies. Since heavier fish lose less weight before they die from terminal deprivation, it is especially important to reduce motivational differences in a given goldfish learning study by restricting fish to a given weight range. It is interesting that difficulty in obtaining goldfish by age has led most investigators to specify length of fish (which is correlated with weight) rather than age in goldfish learning studies. EXPERIMENT2 Fish of all ages took a long time to die when they were placed on terminal deprivation. Exp. 2 was designed to determine if the effects of deprivation are

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reversible after different numbers of days of deprivation. Mammals on deprivation reach a point where it is too late to prevent death by reinstating feeding.

Method Subjects.-Common goldfish (Carassiur auratus) from Grassy Forks Fisheries, Martinville, Indiana were used. The fish were randomly selected from the unused fish obtained for Exp. 1. Deprivation started within 1 to 4 mo. after their arrival at the laboratory. The feeding and housing of fish prior to deprivation was the same as in Exp. 1. Apparatu~and procedure.-The fish were maintained in the same kind of plastic containers used in Exp. 1. Twenty-four 4-mo. fish and 24 16-mo, fish were used in the investigation of recovery from deprivation. Six fish from each age bracket were deprived for 24, 28, 44, or 64 days before feeding was started. An additional 24 4-mo. fish and 24 16-mo. fish served as controls. The control fish were fed daily using the feeding procedure described in Exp. 1. None of the control fish died during the experiment.

Resil1t.r and Dzscz~ssio~z The percentage of fish in each deprivation subgroup which died before feeding was started was similar to the percentage which died in a comparable period for fish terminally deprived in Exp. 1. That is, only one of the 18 4-mo. fish with 24, 28, or 44 days of deprivacion died during the deprivarion period. Four of the 4-mo. fish with 64 days of deprivacion died within 12 days before the end of deprivation. None of the older (16-rno.) fish in the 24- and 28-day deprivation groups died during the deprivacion period. Half the 16-1110. fish in the 44- and 64-day deprivacion groups ( 3 in each group) died before deprivation was terminated. Wich one exception, all fish which survived deprivation did not die after feeding was started. The surviving 24-, 28-, 44-, and 64-day deprivation fish (4- and 16-mo.-old) were successfully maintained with food for at least 44 days after deprivation was ended. By the end of 44 days of feeding the fish were almost as large as control fish that had not experienced deprivation. Not only do goldfish survive for long periods of time wichouc food, the effects of deprivation can be reversed for surviving fish after 64 days of deprivacion. REFERENCES

BOLLES, R. C., & PETRINOVICH, L. Body weight changes and behavioral attribures. Journal of Comparative and Physiological Psychology, 1956, 49, 177-180.

CAMPBELL, B. A., TEGHTSOONIAN, R., & WILLIAMS, R. A. Activity, weight loss, and

survival time of food-deprived rats as a function of age. Journal of Comparative and Physiological Psychology, 1961, 54, 216-219. KIRK, R. E. Experimental design: procedu~esf w the behavioral sciences. Belmont, Calif.: Bcooks/Cole, 1968. TREICHLW, F. R., & HALL,J. F. The relationship between deprivation wei ht loss and several measures of activity. Journal of Comparative and ~hyriolo~ica&~rycholo~~, 1962, 55, 346-349. Accepted March 21, 1975.

Survival time and weight loss in goldfish (Carassius auratus).

Psychological Reports, 1975, 36, 979-985. @ Psycho!ogical Reports 1975 SURVIVAL TIME A N D WEIGHT LOSS IN GOLDFISH (CARASSIUS AURATUS)' ALLEN H . WO...
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