Fish culture technology using double net system for hybrid grouper (brown marbled grouper Epinephelus fuscoguttatus × giant grouper Epinephelus lanceolatus) and rabbitfish (Siganus canaliculatus)

Fish culture technology using double net system based on trophic level predicted can improve productivity. The aim of this research was to evaluate a fish culture technology of grouper and rabbitfish using double net system based on trophic level. This research was conducted with different stocking density. The net used was double net system. The Outer net HDPE with four cage with size of 4 × 4 × 4 m/cage and inner net HDPE with size of 3 × 3 × 3 m/cage. Inner net cage was stocked 20 grouper fish/m3 while outer net was stocked with different density of rabbit fish, 6 fish and 12 fish/m3. Each treatment was duplicated. The result showed the hybrid grouper production up to 205 kg with an individual final weight of 743 g while production of rabbit fish with stocking density 6 and 12 fish/m3 consequently was 10 kg with an individual final weight of 143 g and 15 kg with an individual final weight of 148 g. N and P content in hybrid grouper meat from feed consumed were 25% total N and 11 % total P, however 52 % of N and 74 % of P were released as faeces and excretion to the water. Rabbitfish with stocking density of 12 fish/m3 was the most effective production using double net system.