Effect of low-temperature incubation of channel catfish Ictalurus punctatus eggs on development, survival, and growth

To determine whether the embryonic period of channel catfish Ictalurus punc tatus could be extended at low temperatures, fertilized channel catfish egg s were incubated at five constant water temperatures: 4, 11, 16, 21, and 26 C. Low-temperature incubation of catfish eggs extended the embryonic perio d at 16 (244%) and 21 C (56%) when compared to the control hatchery incubat ion temperature of 26 C. All eggs incubated at 4 and 11 C died within 24-48 h. Developmental stage had a significant (P < 0.05) effect on percent hatc h at 16, 21, and 26 C. Eggs held at 16 C prior to embryonic axis formation died within 48 h. Larvae from eggs hatched at 16 C were incompletely develo ped and died upon acclimation to 26 C for growth tests. Growth of fry reare d at 26 C, following egg incubation at 21 C, paralleled that of fry from eg gs incubated at 26 C. The underdevelopment of fry at 16 C combined with the significant effect of egg stage on survival at this temperature suggests t hat 16 C is below the lower thermal tolerance limit for normal development in this species. The period prior to the formation of the embryonic axis ma y be considered a vulnerable stage in channel catfish development. Increasi ng the embryonic period through low temperature incubation would increase t he duration of juvenile availability for researchers and commercial operati ons.