SELECTION OF POTENTIAL YY MALES OF NILE TILAPIA Oreochromis niloticus (LINNAEUS, 1758) AND EVALUATION OF THE PERCENTAGE OF MALES OBTAINED

Abstract

Successful development of YY technology depends not only in the identification of YY males (YYM), but also on the evaluation of the percentage of males obtained from them. The progeny of selected potential YYM was evaluated individually in order to determine its genetic status. In total, 12 potential YYM and 12 normal females (XX) were selected. Potential YYM were selected taking into account external color, shape of the genital papillae and size. After individual crossing, a confirmed YYM was crossed consecutively with three XX females and three XY females to further assess the variation in the percentage of males obtained. A significant deviation from the 1:1 sex ratio expected for normal males (XY) was observed for ten of the twelve potential YYM that were evaluated, confirming YY status. Variation ranking between 88 to 93% in the percentage of males was observed in crosses between YYM and XX females. Finally, failure to obtain only 100% males was observed in crosses between YYM and XY females. This variation could be the result of the interaction of minor genetic parental factors or the water temperature during fry period. External parameter used for selection of potential YYM need to be optimized in further work.