BROODSTOCK, SPAWNING, AND EGG HANDLING 173 



Figure 59. Injection of hormone intraperitoneally into female channel catfish. 

 (Fish Farming Experimental Station, Stuttgart, Arkansas.) 



2,000 lU spawned three days after they were injected. Female crappies in- 

 jected with 1,000 lU spawned 2 days later at a water temperature of 62°F. 

 Channel catfish, striped bass, common carp, white crappies, and large- 

 mouth bass, injected with 1,000 to 2,000 lU of HCG, also have been in- 

 duced to spawn. 



Hormone injection of striped bass has proven to be effective for spawn- 

 ing this species in rearing tanks. Females given single intramuscular injec- 

 tions at the posterior base of the dorsal fin with 125 to 150 lU of HCG per 

 pound of broodfish show the best results. Multiple injections invariably 

 result in premature expulsion of the eggs. Injection of males is recommend- 

 ed for obtaining maximum milt production. Fifty to 75 lU per pound of 

 broodfish should be injected approximately 24 hours prior to the anticipat- 

 ed spawning of the female. 



Channel catfish also can be successfully induced to spawn by intraperi- 

 toneal injections of HCG. One 800- lU injection of HCG per pound of 

 broodfish normally is sufficient. Two 70-IU injections of HCG per pound 

 of broodfish, spaced 72 hours apart, will induce ovulation in walleyes. 



Egg Incubation and Handling 



Eggs of commonly cultured species of fish are remarkably uniform in their 

 physiology and development. A basic understanding of the morphology 

 and physiological processes of a developing fish embryo can be of value to 



