Selection response and genetic parameters for growth in North African catfish, Clarias gariepinus (Burchell, 1822)

The North African catfish, Clarias gariepinus (Cga) is economically important and has been cultured worldwide. There had previously been no genetic improvement programs for this species, and thus its genetic potential had not been explored or utilized. A selection program to improve growth of Cga has now been established in Thailand and the response to one generation of selection and genetic parameters are presented in this study. The selection was performed by selecting the 17 families that had the highest average EBV (estimated breeding value) for body weight at harvest, while fish from 17 families with medium family EBV were kept as the control group. When they reached maturation, mating was done within groups following a partial factorial mating design which eventually resulted in 51 full-sib (14 paternal-, 13 maternal half-sib families) for the selected group, and 62 full-sib (16 families each of paternal- and maternal half-sibs) for the control group. The families were tagged by family at 100 DAH and communally reared in two 400 m2 earthen ponds. The dataset at 160 DAH (n = 6920) was used to estimate variance components using a multiple-traits animal model by an Average-Information Restricted Maximum Likelihood procedure. Heritability for body weight (BW), total length (TL) and standard length (SL) was low and almost equal (range of 0.128–0.129) and heritability for condition factor (K) was 0.155. Genetic correlations between growth traits ranged from 0.966 to 0.996 and between growth traits and K were 0.294–0.509. Selection response, measured as the difference between least squares mean of the selected and the control groups was 28.00 g (10.37%). Selection resulted in 3.65, 3.77, and − 0.95% correlated response for TL, SL and K, respectively. Despite of a desirable selection response, there is a concern that apparent reduction of heritability may result in low selection response in succeeding generations.