Coral trout grouper Plectropomus leopardus aquaculture is being developed in Indonesia. Grouper aquaculture mainly use trash fish as feed. Therefore, the study to improve utilization of artificial feed is needed. Probiotic has good impact to host; one of them is to improve fish growth. Three probiotics were isolated from digestive tract of coral trout grouper in previous study. The probiotics are B. subtilis BS3, B. amyloliquefaciens BS4, and B. cereus BS6. The aims of this study were to evaluate the effectivity of the probiotics in improving fish growth.
Fed were formulated with protein content 44,49–45,24%, fat content 11,10–11,69% and energy 4.305,00-4.321,61 kkal GE/kg feed. This research was designed using Completely Randomized Design with 4 treatments: 1). Feed without the addition of probiotics, 2). Feed with addition 1% B. subtilis BS3 3). Feed with the addition 1% B. amyloliquefaciens BS4, 4). Feed with the addition 1% B. cereus BS6. Juvenile coral trout grouper with total length 4,11±0,26 cm and body weight 0,99±0,20 gram were reared in 100 liters fiberglass tanks. Fish were fed twice daily by ad satiation method.fish were reared for 12 weeks. Water quality during treatment were maintained: temperature 26.4-29.8°C, pH 8.03-8.20, DO 5,8-6,5 mgL-1, ammonia <0,0523 mg L-1 and nitrite 0.0024-0.0056 mg L-1. Parameter observed were final weight, feed consumption, specific growth rate, protein retention, lipid retention, feed conversion rate and survival rate of coral trout grouper fed four treatment diets.
Results showed that treatments feed with probiotic gave higher final weight, specific growth rate, protein and lipid retention. Feed convertion rate were higher in treatments without probiotics. The survival rate did not affected by the treatments and feed consumption increase as follow the growth.
The highest growth performance were showed by treatments 4 with the lowest feed conversion rate.