Efficacy of 17-alpha-methyltestosterone in the production of male fry of Oreochromis niloticus and study of their survival and growth in the first phase of breeding

Oreochromis niloticus is a species of tilapia in which males grow well compared to females. In order to contribute to the improvement of the breeding of this species, a study was carried out on the production of male fry by the incorporation of the hormone 17-alpha-methyltestosterone in the feed in the first phases of breeding. The survival and growth in concrete tanks of fry produced were studied during the first phase of breeding at a density of 25 fry m-3. The results indicate that the use of 17-alpha-methyltestosterone at a dose of 60 mg Kg-1 of food produced 97.69% of males. Besides, during the first phase of breeding, the growth of fry fed with hormone feed appears to be good (0.80 ± 0.18 g d-1) compared to that of untreated fry (0.52 ± 0.03 g d-1). As for the survival of the fry, it was not influenced by the use of the hormone in the ration. These different results will prompt further studies on the most effective doses of the hormone and the most suitable breeding structures for the success of masculinization.