Growth, Carcass Traits, and Oxygen Tolerance of Diploid and Triploid Catfish Hybrids

Allotriploidy was successfully induced in two hybrid catfishes: Female channel catfish Ictalurus punctatus × male blue catfish I. furcatus (3n = 87) and channel catfish × white catfish I. catus (3n = 82). No significant differences were detected in growth, feed conversion, gonadosomatic index, or dress-out characteristics between diploid and triploid channel catfish × blue catfish raised in 1.3-m-diameter tanks, with the exception of a higher (P = 0.03) condition factor (K) for triploid hybrids. All diploid hybrids had normal gonadal development and histology; however, triploid hybrids were probably not fertile and had abnormal gonadal development, with a single ovary present in 36% of the triploid females. Both testes were present in all males; however, triploid hybrid males had abnormal histology, with no sperm present in seminiferous tubules. Sex ratios did not differ from 1:1 at 14-18 months of age. Growth rate, dress-out percentage, and visceral fat percentage of diploids and triploids did not differ for either of the hybrids in ponds. Although not significantly different, dress-out percentage of triploids was consistently lower than that of diploids. Head weight percentage did not differ between triploid and diploid channel × blue catfish. Tolerance of low dissolved oxygen was higher (P < 0.05) for diploid hybrids than triploid hybrids. Survival of triploid hybrids was equal to or greater than that of diploid hybrids in ponds, but the differences were not statistically significant. Channel × white triploids were morphologically more similar to their maternal parent than their paternal parent; the opposite was observed for channel × blue triploids.