Formation of Male Sex Tilapia Larvae (Oreochromis niloticus) Using Natural Methyltestosterone Hormone

Aims: Obtaining a productive tilapia, by changing the sex of the tilapia larvae into male monosex. This was achieved by determining the effect of the duration of administrating the natural methyltestosterone (MT) hormone on the male sex of tilapia using the Immersion method. Methodology: The study was conducted at the Northern Region Marine and Fisheries Service Branch, Wanayasa Freshwater Fish Seed Development Center, Purwakarta Regency, West Java Province, Indonesia. The experimental design used a completely randomized design (CRD) with 5 treatments and 3 replications. The study used the Immersion method where untreated tilapia and the four hormones tilapia. The treatments are as follows: A = untreated tilapia B = tilapia treated in 17a-MT (5h-100mg/L) C = tilapia treated in MT (5h-350mg/L) D = tilapia treated in MT (10h-350mg/L) E = tilapia treated in MT (15h-350mg/L) Results: Tilapia larvae used were aged 6 days after hatching and reared for 40 days, then the male and SR sex were observed. The results of this study showed that the duration of immersion of tilapia larvae using natural MT significantly affected the male tilapia which resulted in the highest male percentage at 15 h of immersion of 80.2%, then followed by 10-h immersion of 75.6% with the same SR value of about 90%. Conclusion: Administration of natural MT using cow testis meal by immersion method at different durations significantly affects male sexual development in 6-day-old tilapia larvae. Based on the obtained data analyses, the percentage of male tilapia in the 40-day experimental study shows the most effective duration in treatment E (15 h) with a measure of 350 mg/l, which is 80.2%. Further studies regarding the relationship between sex change and the growth of sex-changed fish as an effect of immersion duration.