Response to Selection for Body Weight of Walking Catfish, <i>Clarias macrocephalus</i> (Giinther) after Two Generations of Bi-Directional Mass Selection

Abstract

A study was conducted on divergent lines of Walking Catfish (Clarias macrocephalus) to assess the response to mass selection for body weight at Kasetsart University, Thailand. Broods of C. macrocephalus used in this experiment were seventh generation progeny of a base population originating from random mating of six natural population. Mass selection for body weight was performed at 10 month of age in the high and low line directions. Fifty pairs of F₂ selected brooders from the two divergent lines were individual-mated to produce second generation offspring. Fish were reared in indoor tanks for 7 weeks and in cages for 26 weeks to determine response to bi-directional selection for body weight. Significant divergence in body weight and length of the low and high line occurred at 29 and 33 weeks of age. Response to selection for body weight, measured as the half of the divergence between low and high line, after two generations was 4.16 g (4.16%) and 3.19 g (3.4%) at 29 and 33 weeks of age, respectively. Total length difference between the high and low line was 0.35 cm (1.64%) at 33 weeks of age. Selection differential between divergent lines could have underestimated response in one direction and generated asymmetry in response between selected lines.

J. Inst. Agric. Anim. Sci. 2003 24:67-74