Aspects of a Monosex Population of Oreochromis Niloticus Fingerlings Pro duced Using 17-α Methyl Testosterone Hormone

Abstract

The study investigated the efficacy of 17-α methyl testosterone hormone in producing a mono male sex population in Oreochromis niloticus fry under tropical conditions in ponds in Zimbabwe. Fry were randomly stocked in ten fry tanks at 15000 fry per tank. Five randomly selected tanks received androgenised feed with 17- α methyl testosterone (M T hormone). The other five tanks received feed which had not been treated with 17-α methyl testosterone. The sex ratios, feed conversion ratio, growth rate and survival were established after three months. Fry fed to a diet treated with MT had a significantly higher growth rate as compared to those fed to a non hormone treated diet. Individuals whose diet was androgenised had a higher survival rate as compared to those individuals whose diet was not treated. We concluded that MT has a high efficacy in producing a male population in O. niloticus under tropical conditions and that treatment duration during cold periods be increased to 30 days as compared to the usual 21 days currently being used at Lake Harvest Aquaculture Zimbabwe so as to produce a male population above 95% for optimality.