Thăm dò kỹ thuật chuyển giới tính cá mó (Cheilinus undulatus) trong thời kỳ mang trứng bằng cách tiêm hormone 17α – Methyltestosterone

The artificial sex change in humphead wrasse (Cheilinus undulatus) was examined. Nine of individuals  of  mean  body  weight  (BW)  3.2  ±  0.2  kg  were  treated  with  17α – Methyltestosterone (MT). MT was administered intramuscularly three times at the dose of 0 mg.kg-1 (Treatment 1 – T1), 5 mg.kg-1 (Treatment 2 – T2), and 10 mg.kg-1 (Treatment 3 – T3) every 30 days. After 60 and 120 days of injections, the gonad sections of all fish sampled from T2 and T3 were observed. The result showed that spermatocytes were mostly detectable in the  gonads  of  two-thirds of  experimented  fish of  T2  and  T3  after 60  days of  injection. 100% of fish of these two treatments were shown to have gonads with spermatid after 120-day injection. In T2 (5 mg.kg-1) there were two fish with sperm in the gonads, higher than T3 (10 mg.kg-1), with only one fish. In control treatment (T1), however, only oocytes of phases II, III were found in the gonads. The result also indicated that induction of female-to-male sex inversion  in  juvenile  Cheilinus  undulatus  by  MT  (5  and  10  mg.kg-1)  within  180  days  of injection was completely effective with white milt.