Determination of Age of Oreochromis niloticus Fry After Hatching for Efficiency of 17-alpha Methyltestosterone on Sex Reversal

The aim of this research was to determine age of Oreochromis niloticus fry after hatching for efficiency of 17- methyltestosterone on sex reversal. The study was carried out in Zoology Laboratory, University of Eldoret. Fish were seined from University of Eldoret fish farm and those brooding eggs and fry were selected. Fry were fed using the feed containing 17 methyltestosterone for varying periods of days. The period of exposure to hormone feed were distributed into 21 days, 30 days, 42 days and 60 days. And at the end of each period, the fry were then sampled in three replicates of ten fry for dissection and microscopic examination. The data was statistically analyzed using Two-way Analysis of Variance and correlations, Statistical Programme for Social Scientists and Excel Statistical package. In all the treatments, no pure females were observed but intersex of varying number of ova was observed. The yolk sac fry from the incubator had 100 % conversion efficiency into males both at 21 and 60 days of exposure to hormone, while other groups did not attain 100 % conversion into males.