Feed intake in channel catfish: is there a genetic component?

Increasing catfish growth is a primary objective of our broodstock improvement programme, and growth is at least partly dependent on voluntary feed intake. Two experiments were conducted to determine the genetic component of feed intake, and the relationship between feed intake and growth in sib‐groups of channel catfish. In the first experiment, 10 fish from each of 31 full‐sib families from the USDA‐103 strain of channel catfish, Ictalurus punctatus (Rafinesque), were individually identified with passive integrated transponder (PIT) tags and distributed into two replicate tanks, five fish from each family to each tank. Fish were fed to apparent satiation with feed labelled with an X‐ray opaque marker for one meal, radiographed, and feed intake was quantified for each individual. Genetic effects (broad sense heritability) accounted for approximately 41% of the phenotypic variation in feed intake. These fish were then grown for 5 months and the mean change in weight of the family groups was significantly correlated with mean feed intake (r = 0.64, P