Oral Administration of Testosterone in Fish Diet Affect Sex Differentiation and Testis Development in Tilapia.

Fries of Tilapia Zillii, Tilapia Nilotica and Red Tilapia were fed hormone-free (control diet) and hormone treated diets of 30% crude protein. Methyl-testosterone (Mt) was incorporated in the diets at 3 levels (60 ,120 and 200 mg Mt / kg feed ) and administered to 7 days post hatching fries for a period of 28 days. Maleʹs ratios after 30 days post-hormone treatment substantially differ from control. 86.7-90% males were produced with low dose of 60 mg Mt / kg feed. Higher dosage levels of 120 and 200 mg Mt / kg feed had an inhibitory effect on oogenesis, the degree of inhibition was dependent on the level of androgen and fish species. Remarkable propagation of somatic element in gonads occurred and a high % of neutral gonad was noticed at hormonal level of 120 and 200 mg Mt / kg feed. Plasma testosterone level decreased significantly in six mothsʹ old sex inversed males (fed diet of 60mg Mt / kg feed ) compared to control specially in Tilapia Nilotica and Tilapia Zillii. Histological characteristic of mature sex reversed males show spermatogenic cysts with cells in early stages of development were predominating while in control testes cysts with predominant spermatozoa were seen.