Lipid is one of the most important nutritional factors affecting growth and survival of larval fish. This study aims to determine optimum level of lipid in formulated microdiets for the 10-day old rockfish (Sebastes schlegeli) larvae. Five granulated microdiets (CL11, CL14, CL17, CL20, and CL23) containing various (11%, 14%, 17%, 20%, and 23%, respectively) levels of lipid were prepared, and their lipid levels were controlled by adding fish oil at the expense of dextrin. The effects of feeding rockfish larvae with these formulated microdiets were compared with two commercial microdiets (Belgium and Japan), and local crumble diet. At the end of the 29-day feeding trial, weight gain (%) and total length (mm) of larval fish fed the CL20 diet were significantly (P 0.05) affected by the experimental diets. Crude lipid content of the whole-body fish was relatively well reflected from lipid levels of the experimental diets. In conclusion, the greatest weight gain and longest total length were obtained in larval fish fed the CL20 diet among the experimentally formulated microdiets. The optimum lipid level in the experimentally formulated microdiet was estimated to be 17.3% for rockfish larvae based on the broken-line analysis.
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