Effects of mesterolone on growth and sex-ratio of the Nile tilapia (Oreochromis niloticus Linnaeus)

Mesterolone, an androgenic hormone, was fed to the sexually undifferentiated fry of Nile tilapia Oreochromis niloticus , for a period of 42 days at four different doses such as 50, 100, 150 and 200 mg/kg feed. At the end of the hormone feeding phase, the fry of the treatments fed on 50 and 100 mg/kg mesterolonetreated feed gained significantly higher length and weight than those of the fry fed on 150 and 200 mg hormone/kg feed and the control diet (0 mg/kg). A 100 % sex-reversal was obtained in the group fed on 200 mg mesterolonetreated diet. The sex-ratios of fish of the groups fed on diets containing 150 and 100 mg hormone/kg were found to be skewed towards male…