DETERMINATION OF THE EFFICIENCY OF 17-α METHYLTESTOSTERONE ON SEX REVERSAL OF NILE TILAPIA, OREOCHROMIS NILOTICUS AT DIFFERENT DEVELOPMENTAL STAGES

Abstract

The aim of the study was to determinate the efficiency of 17-α methyltestosterone on sex reversal of Nile tilapia, Oreochromis niloticus at different developmental stages. Fish were seined from Eldoret fish farm and those brooding eggs and fry were selected. The brood was emptied into a bucket containing aerated water. The fry and eggs were transported to the laboratory for further processing. Eggs were incubated in the incubation jar while fry were transferred into aquaria. The fry were sorted out according to age stages and sex reversed using 17-α Methyl-testosterone incorporated into a diet at 40mg per kilogram of feed. The hormone supplemented feed was prepared by weighing, using digital weighing balance the desired quantity of the hormone, dissolving it in 95% ethanol and spraying it on the feed. The feed was then dried under shade. The age stages included 8 days, 23 days and 40 days after hatching. The fry were fed on food containing methyl-testosterone for a period of 21 days, 30 days, 42 days and 60 days. Sex of fingerlings was determined through microscopy and sex identification was facilitated by staining the gonads using aceto-carmine. Water quality parameters were measured weekly and room temperature was controlled using adjustable fan heater and thermostat dipped in water. Female fingerlings were not observed while male and intersex percentages were 92.2% and 7.8%, respectively. The age of fingerlings was significant in determining fingerlings‟ sex. Pearson and Spearman‟s rho correlations was highly significant at (P<0.05) while hormone supplemented food in days and sex of fish showed no significant. Pearson Correlation between hormone supplemented food and age of fish showed high significance at (P<0.05). According to this study, is recommended that sex reversal for O. niloticus should start at the age of eight days after hatching for a period of twenty one days of hormone supplemented food feed.