offspring, and predation by adults can be 

 minimized or eliminated. 



Figure 1. --One of the more reliable characteristics of an imminent 

 spawner is the raised portion of the body wall behind the 

 pelvics. 



Males of a size comparable to our 

 smallest gravid females (12.6 inches, total 

 length) contained motile sperms (as 

 proved by many autopsies). Such 

 m^les when paired with females of 

 similar size successfully fertilized 

 the eggs. Therefore, less attention 

 was given to the characters of the 

 males than the females, but males 

 with prominent secondciry sexual char- 

 acteristics — a head wider than the 

 body, darkly pigmented under jaw and 

 belly, and large, protruded genital 

 papilla — usually possessed better- 

 developed testes (fig. 3). Such 

 males were sometimes used success- 

 fully a second time, whereas those 

 with poor secondary sexual characters 

 did not completely fertilize a second 

 spawn, although they participated in 

 the second spawning act. 



COLLECTION AND CARE OF 

 BROOD STOCK 



Some of the brood fish used 

 for pituitary- induced spawning were 

 collected from the natural waters 

 of Oklahoma in 1955 and 1956 and 

 kept in hatchery ponds until used 

 in 1957. Other catfish were col- 

 lected from natural waters shortly 

 before spawning time in 1957. The 

 brook stock kept in the hatchery 

 was fed a diet of one-third liver 

 and two-thirds dry pellets which 

 were about 36 percent protein. 

 Early experiments showed that fish 

 fed only pellets did not exhibit 

 good gonadal development and were 

 more than normally susceptible to 

 gill diseases and parasites. 



m^ 



Figure 2 . 



-The opening of the oviduct in female channel catfish is 

 immediately posterior to the anus and separate from the 

 more posterior urinary opening . In the breeding season 

 folds of skin on each side of the uro-genital openings are 

 raised and divided by a groove. 



Ordinarily, in regular hatchery proce- 

 dures,- the injection of pituitary materials 

 merely precipitates the spawning act sind 

 does not induce spawning if the female is 

 not already in or nejir a spawning condition; 

 therefore, the care and selection of females 

 is extremely important, as will be pointed 

 out in greater detail later. The best mor- 

 phological characters indicative of spawning 

 condition in the female are a well-rounded 

 abdomen, the fullness of which should extend 

 posteriorly past the pelvics to the genital 

 orifice (fig. 1). The ovaries should be 

 palpable and soft, and th6 genitals raised 

 and reddish (fig. 2). 



FACILITIES FOR SPAWNING 



Fish were induced to spawn in glass 

 aquaria with capacities ranging from 5 to 

 50 gallons. Metal trout-rearing troughs, 

 divided into compartments, were also used, 

 but they were considered less satisfactory 

 because the fish jumped against the divider 

 and cover screens and injured themselves 

 much more than did those in aquaria. In 

 addition, only 1 female spawned of 13 fe- 

 males placed in metal troughs and injected 

 with pituitary material that was proved to 

 be potent in other experiments. Successful 

 use of troughs was suggested by another 



