BROODSTOCK, SPAWNING, AND EGG HANDLING 137 



REMARKS 



Eggs can be successfully incubated at constant temperatures between 55° and 75°. Hatching 

 success may be lower at 50° and 80°. The eggs may be especially sensitive to sharp changes in 

 temperature during early development. 



and small enough to be easily captured and consumed. The pond should 

 be free of filamentous algae or rooted vegetation that might provide cover 

 and escape for the forage fish. Pond edges with a minimum depth of 2 feet 

 permit the predator fish to range over the entire pond and readily capture 

 the food provided. 



The holding pond should be inspected at 2- to 3-week intervals, and 

 seine samples of forage fish should be taken throughout the summer, fall, 

 and spring months. When samples taken with a 15-foot seine contain fewer 

 than 15-25 forage fish of an appropriate size, the forage should be replen- 

 ished. Tadpoles, crayfish, bluegills, and miscellaneous other fishes that 

 may accidentally develop in the pond cannot be depended upon to satisfac- 

 torily feed the hatchery broodstock. Instead, a suitable forage species 

 should be propagated in adequate quantities to assure both maintenance 

 and growth of the cultured species. 



Maintenance of broodstock represents the first phase of activity that 

 must be accomplished in channel catfish culture. Broodfish in most situa- 

 tions are domesticated strains that have been hatchery-reared.. Dependable 

 spawning cannot be obtained until female fish are at least 3 years old, 

 although 2-year-old fish that are well-fed may produce eggs. Females 

 weighing 1-4 pounds produce about 4,000 eggs per pound of body weight. 

 Larger fish usually yield about 3,000 eggs per pound of body weight. Fish in 

 poor condition can be expected to produce fewer eggs and lower quality spawn. 



