ALI ABUMHARA A., MAHMOUD YADEM S., SOVJAK R.
Abstract
This study was conducted to develop a short-term immersion procedure for masculinisation of Nile Tilapia (Oreochromis
niloticus) by using 17á-methyltestostrone at 100, 200 or 400 ìg/l for 3, 6 or 12 h. Fry were immersed tow successive times
with 3 days interval period. The highest percentage of male Oreochromis niloticus (96 ± 4%) and the lowest gonado-somatic
index of female Oreochromis niloticus (1.89 ± 0.02) were obtained by immersion of Fry in 17á-methyltestosterone at the
level of 400 ìg/l for 6 h. However, survival rate of Oreochromis niloticus Fry during hormone treatment period did not differ
signifi cantly from survival rate in the control group.
Key words:
tilapia; androgen; methyltestosterone; oreochromis niloticus; sex reversal; males; sex ratio