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Four semi-purified diets, containing crystalline amino acids (CAAs), were fed to juvenile red sea bream, Pagrus major in order to ascertain the ideal dietary amino acid pattern for this species. A control diet containing 50% casein-gelatin as protein sources, but no CAAs were fed to the fish. The other diets contained 30% casein-gelatin and 20% CAAs. CAAs were added to diets to simulate with amino acid pattern of the red sea bream eggs protein (REP), red sea bream larvae whole body protein (RLP), red sea bream juvenile whole body protein (RJP), and brown fishmeal protein (BFP). The juveniles (average initial body weight, 1.58 ± 0.01 g) were maintained in triplicate tanks and fed twice daily for 30 days. The highest weight gain was observed in juveniles fed the RJP diet. No significant difference was observed in juveniles fed the RLP and BFP diet. Feed efficiency ratio, protein efficiency ratio and amino acid retention in the whole body were significantly (p < 0.05) affected by the simulated dietary amino acid patterns. The essential amino acid profile and A/E ratios of the whole body after the growth trial showed little difference among the dietary treatments. The results suggest that red sea bream juveniles are able to utilize high amounts of CAA in coated form. The amino acid pattern of RJP could be used as an appropriate of reference dietary amino acid for this species.

The key success of producing grouper seed depends on the availability of high and complete nutritive live food (zooplankton) during larvae development stage. Rotifer and Artemia are common zooplankton that has been used in most of grouper hatchery. The cysts of Artemia is expensive because it's still imported, therefore potential zooplankton from Indonesians waters should be developed to replace or to substitute Artemia. Copepod Oithona sp can be found easily in Indonesian marine waters. Oithona sp can be developed to adult stage within 7 days. One female Oithona can produce 8 to 22 nauplii with average 14,39 ± 3,62 nauplii. The larva of humpback grouper (Cromileptes altivelis) fed by Oithona sp showed a higher DHA content (0,30 % b/b) than those fed by copepod + Artemia (0,15 % b/b) and and Artemia only (0,03 % b/b). The EPA content in larva fed by Oithona also showed the highest, 0,30 % b/b. However, improvement technique of monoculture Oithona should be carried out due to mass mortality and contamination by protozoan and rotifer.

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