ORAL ADMINISTRATION OF 17Α-METHYLTESTOSTERON FOR CLIMBING PERCH Anabas testudineus FUNCTIONAL MALE PRODUCTION  

Climbing perch size variation between male and female at harvest reflects the sexual dimorphism in growth rate; female grows faster than male. This phenomenon leads to a high potential for female monosex culture in the future. Monosex female population can be produced by mating functional male and normal female, and functional male can be generated by masculinization using androgen treatment, prior to the timing of sexual differentiation. This research was conducted to established the optimum dosage of 17α-methyltestosterone (MT) hormone to produce the functional males.

In masculinization experiment, 14-days-old juveniles were feed by artificial diet without MT (control) and four different MT contained diets namely 25, 50, 75, and 100 mg of MT per kg diet for 30 days at similar frequency and feeding rate as previous experiment. Male ratios is histologically determined at the end of the experiment.

The result showed that oral MT administration produced four gonads characteristic; male, female, intersex, and sterile (Figure 1 and Figure 2). The fish mortality increasing along with the increasing of MT dosage. Furthermore, the dose of 50 mg MT/kg diet seemed to be an optimum dosage since it result the highest male ratio (88.9%) and potentially generate 61.1% of functional males.