Induced sex change, spawning and larviculture of potato grouper, Epinephelus tukula

The potato grouper ( Epinephelus tukula) is a new aquaculture species with high economic potential. This is the first report of induced sex change, reproduction and larval rearing in this species. The smallest body size at which mature females were observed was 90 cm in total length and 16 kg in body weight. The diameter of tertiary yolk globule stage of oocytes was 505±10 μm for 16–24 kg individuals. Larger oocytes (552±13 μm) were obtained from individuals at 24 kg body weight. Implantation with an androgen mixture (1000 μg/kg body weight) containing testosterone, 17α-methyltestosterone, and testosterone propionate in equal ratios, was applied to female groupers for the induction of sex change in March. Sex change had occurred by 30 days after androgen implantation, and the male ratio reached 66.7% by day 70. Natural mating and spawning activity were found in females and sex-changed males in April. The fertilized eggs were hatched and reared successfully with a series of live foods. Metamorphosis occurred and larvae became juveniles with spots and skin pigmentation by 29.3 mm body length, with complete reduction in the pelvic and dorsal fins by 33 days after hatch.