Effect of Nonsteroidal Aromatase Inhibitor on Sex Reversal of Oreochromis mossambicus (Peters, 1852)

Abstract

In the present study, the efficacy of letrozole, a potent nonsteroidal aromatase inhibitor, and 17a-methyltestosterone on gondal sex differentiation and sex reversal was examined in Mozambique tilapia (Oreochromis mossambicus). Among the doses tried in the experiment, 100 mg letrozole, 200 mg letrozole, and 50 mg 17a-methyltestosterone/kg produced male dominated populations (97-100% males). The combination of 100 mg letrozole+25 mg 17a-methyltestoster/kg yielded 100% males while the combination of 50 mg letrozole+25 mg 17a-methyltestosterone/kg yielded 92% males. The control group consisted of 48.05% males and 51.95% females, close to the normal sex ratio of 1:1. Survival ranged 85.61-94.31% in the treated groups, significantly higher than 73.83% in the control (p<0.05). In general, the letrozole and combination treatments resulted in a slight alteration in the gonadosomatic index of the tilapia. Administration of letrozole alone or in combination with 17a-MT did not adversely affect the proximate composition of the muscle. Results suggest that letrozole and 17a-methyltestosterone have the potential to produce 100% male populations in Mozambique tilapia and that inhibition of aromatase activity influences sex differentiation in Mozambique tilapia.