Tilapia fry were produced by hybridization of males of blue tilapia (Oreochromis aureus) with females of Nile tilapia (O. niloticus) and by sex reversal using oral administration of 3 doses (60, 80 and 100 mg/kg diet) of the androgen 17 α-methyltestosterone (MT) for 28 days. Fry were fattening in earthen ponds for 210 days.
All treatment groups that received androgen MT (T3, T4 and T5) showed sex reversal with a significantly higher males proportion than females as compared to the control (T2) and hybrid (T1) groups. The treatment group that received 60 mg MT (T3) exhibited the best growth performance parameters (average weight gain, average daily gain and specific growth rate) and feed utilization parameters (feed conversion ratio, protein efficiency ratio, protein production value and energy utilization). The highest percentage of body crude protein; ether extract and ash were detected in T3 group. With regard to human food safety, tilapias that treated with MT (T3, T4 and T5) rapidly excrete ingested hormone and MT levels falling to lower concentrations than that in both hybrid (T1) and control (T2) groups.