This second spawn was tended with considerably 

 less vigor than the first, and there were rela- 

 tively few attempts at working the eggs . Only 

 about 10 percent of the eggs of this spawn sue - 

 cessfuUy hatched, many of them dying shortly 

 before or during hatching. He attended a third 

 spawn which also hatched poorly for the same 

 reason s . 



In poor hatching, the eggs in the center 

 of the mass were the ones most affected. A 

 normal, uninjured male is capable of success- 

 fully spawning with at least three females, a 

 fact reported to us by experienced fish-cultur- 

 ists, and also indicated by our experiments . 



POST HATCHING ACTIVITY 



When the eggs hatched the males were 

 removed and the newly -hatched fry accumulated 

 in a mass on the bottom and usually in the comer 

 of the aquarium . They remained in this position 

 for about two days; then they began to come to 

 the surface. At this time the yolk was greatly 

 reduced and the skin pigment was visible. By 

 the third day they started to feed and move 

 about the aquarium, at which time they were 

 transferred to feeding troughs . 



ADDITIONAL SPAWNINGS DURING THE 

 SAME SEASON 



We believe that male catfish can be used 

 for propagation a second time two or three days 

 after spawning, provided that the fish are in 

 good condition and that the eggs of the first 

 spawning are artificially incubated, or each 2 

 weeks if the male is allowed to attend each spawn. 

 Therefore, the number of males in the brood- 

 stock may be reduced to half the number of 

 females . 



Second spawnings of females as well as 

 males within a single season were reported for 

 bullheads by Breder (1935). This may occur in 

 the female channel catfish as an irregular event. 

 A spawning keg was raised to pick up the newly- 

 hatched fish on the seventh day after a spawn 

 had been found, but eggs early in development 

 were there instead. The eggs in the bottom of 

 this mass were dead and it was believed that 

 these had been deposited 7 days previously. The 

 second deposition of eggs had beenmade 3 days 



later, as evidenced by their stage of develop- 

 ment, and the male was attending the eggs . It 

 is possible that the fish were disturbed during 

 the spawning act and did not return until three 

 days later; or the female had deposited eggs 

 without the male in attendance, a possibility 

 which we believe to happen seldom if ever; or 

 the physiological level of gonadotropic hormones 

 was such that spawning was delayed or intermit- 

 tent. 



Four females which were induced to 

 spawn with injected pituitary materials and two 

 that spawned without injections were handled 

 after spawning and no eggs could be stripped. 

 Another uninjected female which had spawned 9 

 days previously was stripped of about a thousand 

 eggs . This female might have spawned a second 

 time, but there is no practical significance to a 

 second spawning when it represents only the left- 

 over eggs of a previously incomplete spawn. In 

 our experience, when female catfish spawn they 

 usually void all their eggs. 



SUMMARY 



Channel catfish, Ictalurus punctatus , were 

 injected with fish pituitaries and spawned in glass 

 aquariums. Although the fish were thus induced 

 to spawn, the basic spawning pattern and behavior 

 reflexes probably were not modified by the in- 

 jections . Rather, any visual, physical, and 

 chemical stimuli which normally cause the fish's 

 own pituitary to secrete the gonadotropins neces- 

 sary to precipitate the spawning act were bypassed 

 by the exogenous gonadotropins, thus causing the 

 fish to spawn. 



During the prespawning period the male 

 drove or hazed the female and often bit her on 

 the flank or caudal peduncle. This activity con- 

 tinued until the female assumed a position on the 

 bottom of the aquarium. They were then con- 

 sidered "paired." 



Both the male and female were belligerent 

 toward other fish, either male or female, when 

 these were added to the aquarium . The degree of 

 aggressiveness seemed to be correlated with 

 gonadal development, but established residency 

 also played a part . 



No particular behavior which absolutely 



