Age at puberty of channel catfish, Ictalurus punctatus, controlled by thermoperiod

One of the major difficulties in selecting for superior traits for the culture of channel catfish is that most fish do not breed until they are three years old. This study was designed to decrease the time necessary to achieve puberty in channel catfish Ictalurus punctatus. Channel catfish, held under a shortened annual temperature cycle of four months of 26 C water followed by two months of 13–14 C temperature spawned at a higher rate (73%) after three temperature cycles than fish held in outdoor ponds on two normal seasonal temperature cycles (10%) or fish raised in tanks supplied with constant 26 °C water (3%). The fish were exposed to constant light in tanks until they were about 22 months old when they were stocked into outdoor spawning ponds with spawning containers. Fish held in constant warm water weighed about 1200 g and were significantly heavier than fish from the other two groups (about 600 g) when stocked into spawning ponds. Spawns from tank raised fish were significantly heavier than spawns from fish held in ponds and the shortened annual temperature cycled fish. These data suggest that the onset of the first reproductive period (puberty) is a developmental event that requires three cycles of warm and cold periods, and that weight and photoperiod have little influence on the onset of puberty.