Optimum levels of crystalline amino acids in diets for larval red sea bream (Pagrus major)

To study the nutritional requirements of essential amino acids in fish larvae, a purified diet is needed, and to assess the optimum level of crystalline amino acids (CAAs) in larval diets, red sea bream larvae (Pagrus major Temminck and Schlegel) were fed five microbound diets with different levels of CAAs. The larvae were cultured for 30 d. Assessment of growth, survival, and body amino acid composition after the culture period indicates that replacing casein with low levels of CAAs is beneficial. Growth and survival were enhanced when 5 g casein per 100 g of diet was replaced with CAAs. The effect of replacing 10g casein per 100g of diet with CAAs was that the larval performance was similar to that of the control diet. However, replacing 15 g or more of casein produced a detrimental effect on larval performance. The amino acid leakage from the diet particles is high and microencapsulation of CAAs is therefore recommended.