Results and Discussion . --The populations were censused over 

 the period October 6-17 and the results are shown in Table 3. 

 There were marked differences between the caged and uncaged popula- 

 tions in both survival and rate of growth. Rates of survival 

 averaged 97.3 percent in the uncaged, and only 70.1 percent in the 

 caged populations. Total lengths in inches (centimeters) averaged 

 10.0 (25.4) in the uncaged, and only 8.2 (20.8) in the caged pop- 

 ulations; final average weights for uncaged fish (0.32 pounds) 

 (145 grams) were twice as heavy as those for fish confined to cages 

 (C.16 pounds) (72.5 grams). The combination of faster growth and 

 higher survival produced final standing crops in uncaged popula- 

 tions that were more than 2.5 times as heavy as those confined to 

 cages (460.6 vs. 173.1 pounds) (208.9 vs. 78.5 kilograms). 



Poor survival and slow growth among the caged fish were 

 believed to be due primarily to a dietary deficiency. The un- 

 caged fish were able to supplement the pelleted rations with natual 

 foods, while the caged fish were limited to the dry, floating ra- 

 tions. The food used was designed as a supplementary feed for pond 

 catfish, and was apparently lacking some essential nutrients gain- 

 ed by the uncaged fish through natural foods. 



No unusual behavior or signigicant mortalities were 

 observed among the caged populations over an initial period of 

 about 80 days, but on about August 1 mortalities increased, and 

 behavior of the fish in certain cages changed rather markedly. 



One common cause of death appeared to be mutilation of 

 certain fish by others. In some cases large sections of muscle 

 were removed from dorsal or lateral areas, and bones of the caudal 

 and anal fins, or of the vertebral column, were often exposed to 

 view, with large "flaps" of loose skin trailing behind. Mutilated 

 fish did not appear to be either the smallest or largest, and fish 

 so mutilated almost always died. Actual biting of one fish by 

 another was never observed, but fine scratches believed to have 

 been made by the teeth of an attacking fish were very much in 

 evidence. 



Two types of abnormal behavior were frequently observed 

 among the caged fish. In one type, an occasional fish could be 

 seen to suddenly swim very rapidly and erratically in a manner that 

 might be described as skipping across the surface. Such activity 

 was short-lived, ceasing as abruptly as it had begun, and the source 

 of motivation was never evident. Also, when the cages were raised 

 in the water to expose the fish to view, some individuals would 



