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.
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