Energy for fish to carry on with its biological activities and growth comes from food that they eat. In artificial diets, protein become the most expensive source of energy so it is necessary to keep the proportion of protein down to the optimum levels for good growth and feed conversion. In another study, prebiotics resulted in good growth of fish using a manufactured prebiotic supplement. Ideally, we want food material available all year, inexpensive and not be in competition with food material for human consumption. In this study, food formulation with prebiotics made from local products were prepared for fish food. In this study sago was the source of carbohydrates, mackerel and land snails were the source of protein. The formulation was fed to humpback grouper Cromileptes altivelis to study the effectiveness on its growth. Ninety humpback groupers (size 9-9.5 cm, weight 10 – 11 g) were reared in 3 fiberglass tanks for four weeks. Each tank had 30 fish, first tank as control without sago and the two tanks with sago in dietary prebiotic pellet. Length and weight gain were recorded every week then growth performance of fish were assessed in the form of Specific Growth Rate (SGR), Food Conversion Ratio (FCR), weight gain daily and length-weight relationship. Food proximate test were carried out separately in the Integrated Chemistry Laboratory, Institut Pertanian Bogor. Data analysis showed a significant difference in the growth performance of humpback grouper through the values of SGR, FCR and average growth daily, between treatment A and B (with sago) and treatment C (control, zero sago). The proximate test displayed lower protein in treatment A (57.95%) and B (55.95%) but higher in treatment C (59.37%), in the contrary to carbohydrate for treatment A (27.80%), treatment B (26%) and treatment C (22.98%).

Fish growth is one of the most target in aquaculture with right method of feeding, water quality and size of cages where they were held. In this study, a 70-day research was conducted to evaluate the effect of floating net cages dimension on growth and survival of trevally Caranx ignobilis in Ambon Inner Bay of Indonesia. A total of 90 juvenile trevallies with an average weight of 17.18 ± 1.9 g was randomly stocked in six floating net cages at three different sizes as treatments in replicate groups. Fish were fed 10% of total body mass with by catch fish twice a day to satiation. Length and weight were recorded, growth performance of fish were assessed in the form of Specific Growth Rate (SGR), Food Conversion Ratio (FCR) and Survival rate (SR). The result showed there were no significant different growth rate (SGR) at different treatments (p>0,05), with the highest SR = 100% and lowest FCR = 2.9 both in treatment C. It means the best dimension of fish rare in this research was at the biggest size of cage 200 × 150 × 100 cm 3.

Due to an equilibration of partial pressure of CO 2 (pCO 2 ) in the atmosphere, 30% of its concentration has been absorbed by ocean and making it more acidic and generate potential global warming. Future changes of ocean pH and temperature are predicted to impact biodiversity of marine ecosystems, particularly those animals that rely on calcification process. Reduced pH will induce dissolution rates of calcium mineral particularly aragonites and calcites and that alter decalcification rates. The reduction of pH also disrupts acid base balance and metabolic rates that lead to metabolic depression whilst increase temperature affects organisms' thermo-tolerance capacity. Even though decreased metabolic rates were associated with metabolic depression, a strategy to match oxygen demand and availability, however prolong exposure to these stressors have affected growth, survival and reproduction rates. In addition, increase CO 2 and temperature have also magnitude end-product metabolites such as succinic and lactic acids and reduced energy nucleotides (adenosine 5-triphosphate, adenosine diphosphate and adenosine monophosphate) in the cells, indicating an increased reliance on anaerobic metabolism.