Survival, growth and selection in a communally reared multifactorial crossof African catfish (Clarias gariepinus)

Selection of fish has been constrained by the difficulties of communal rais ing due to the lack of a reliable tag for small fish. We have overcome this problem by the mixed rearing of the progeny of a complete 4 x 4 factorial cross of African catfish (Clarias gariepinus) in a single tank and microsat ellite DNA fingerprinting a subsample at 1 month and 9 months of age. Simul taneously, these fish were scored for several phenotypic traits. Eighty fiv e to 91% of all fish were identified uniquely on the basis of nine microsat ellite DNA markers. The survival rare was affected by dam at 9 months of ag e. Dam and family effects were prominent in all phenotypic traits measured at 1 month of age, while sire and family effects were prominent at 9 months of age. Selection of the best growers on the basis of mass selection or fa mily selection did not affect genotype probably because of the limited gene tic background of the broodstock. Phenotypically, growth rate of the mass-s elected group turned out to be higher than the family-selected group. (C) 1 999 Elsevier Science B.V. All rights reserved.