Performance testing of clonal Oreochromis niloticus lines

Abstract

Six different homozygous clonal lines (343 adult fish) were established by gynogenetic reproduction of mitotic gynogenetic Oreochromis niloticus females. Second generation clones (494 adult fish) were obtained by gynogenetic reproduction of clonal females. The clonal status of the fish was proven by the alloenzyme adenosine deaminase and DNA fingerprints. Performance testing of the all-female clonal groups was carried out in comparison with adequate heterozygous control,groups. Up to first feeding, clones showed a significantly reduced mean survival rate (4.0%) if compared with offspring of normal heterozygous fish (43.9%). Reproductive traits of the second generation clones varied between and within clonal lines, Mean body weight differences at 136th day of life between all-female clonal groups (45.5 g), kept under three different density classes, and corresponding all-female heterozygous control groups (50.2 g) were not significant. Variation of body weight was significantly lower in all-female homozygous clones (coefficient of variation: 23.1%) than in all-female heterozygous controls (coefficient of variation: 34.1%). Possible reasons for phenotypic variation between isogenic O. niloticus individuals are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.