Abstract
In the present study, effect of different dose rates of synthetic androgen 17 alpha methyl testosterone (MT) i.e. 50,
60, 70 and 80 mg/ kg of feed, on sex reversal and growth performance of Nile tilapia was evaluated. MT was
administrated orally by using 40% crude protein diet to tilapia fry for 25 days in glass aquaria. After this period fry
was shifted to earthen ponds to monitor its growth performance for 280 days (20 fortnights). At the end of
experiment the sex ratio was determined by examining gonads after dissecting the fish. Growth performance was
monitored by recording the morpho-metric characteristics i.e. wet body weight and total length of fish on
fortnightly basis. The results of the present study showed that all MT receiving treatments showed a significantly
higher male proportion than control. Dose rate of 70 mg MT/ kg of feed resulted in maximum male population
(95.4%) with 1% female and fewer intersexes (2%). The dose rate of 70 mg MT gave the maximum gain in body
weight i.e. 283.2 g, resulting in maximum fish production i.e. 3342 kg/ha./year, 1.6 times greater than control.
