청틸라피아 (Oreochromis aureus)의 자어에 0, 1, 10, 60 ppm의 $17alpha-methyltestosterone$(MT)을 30 일간 사료에 섞어 먹인 후 다음 57 일간을 0 ppm을 먹인 그룹은 다시 세그룹으로 나누어 0 ppm MT (0-0), 10 ppm MT (0-10), 및 60 ppm MT (0-60)을 먹였고, 60 ppm 을 먹인 그룹은 다시 3 그룹으로 나누어 0 ppm MT (60-0), 10 ppm MT (60-10), 및 60 ppm MT (60-60)을 먹였으며, 초기 30 일간 1 ppm과 10 ppm MT를 먹인 것은 계속해서 1과 10 ppm을 먹여서 체조성과 생식소 중량지수에 미치는 영향을 조사하였다. 초기 30 일간 어체의 조단백과 조지방은 MT 농도와 역상관 관계를 보였고, 수분 함량은 순상관 관계를 보였다. 후기 57 일간에 먹인 MT는 초기 30 일간 먹인 MT 보다도 숫컷의 체조성에 더 큰 영향을 미쳤다. 사료 중의 MT는 초기 30 일간이나 후기 57 일간 모두 숫컷의 생식소 중량지수에 나쁜 영향을 보인 반면에, 암컷의 경우에는 후기 57 일간에 사료 중의 MT 양이 생식소 중량지수에 나쁜 영향을 나타내었다.
Blue tilapia, Oreochromis aureus swim-up fry were fed,0, 1, 10, or 60 ppm $17alpha-methyltestosterone$(MT) for 30 days (sex reversal period). Fish that had been fed 0 ppm MT during the sex reversal period were subsequently fed 0 ppm MT (0-0), 10 ppm MT (0-10) or 60 ppm MT (0-60) for the next 57 days (post sex reversal period) ; fish that had been fed 60 ppm MT during the sex reversal period were subsequently fed 0 ppm MT (60-0), 10 ppm MT (60-10), or 60 ppm MT (60-60) during the post sex reversal period. One group was fed 1 ppm MT (1-1), while another group was fed 10 ppm MT (10-10) during the entire 87-day experiment. There was a significant inverse relationship between concentration of MT and percentage body protein and percentage body fat at the end of the sex reversal period, while there was a significant positive relationship between concentration of MT and percentage body moisture. MT treatment during the post sex reversal period had greater effects on body composition of males at the end of the post sex reversal period than did MT treatment during the sex reversal period. There was a significant inverse relationship between MT concentrations, during both the sex reversal and post sex reversal periods, and gonosomatic indices (GSI) in males. In females, there was a significant inverse relationship between MT concentrations during the post sex reversal period and GSI.
