A six-week feeding trial was conducted to estimate the optimum dietary essential amino acids (EAA) pattern for silvery-black porgy juvenile (initial weight 4.7g) based on the AA deletion method. Eleven isonitrogenous and isoenergeticdiets were formulated containing 60% of fish meal and 40% of crystalline AAas the main nitrogensource and, in the control diet the EAAprofile was made similar to fishmeal protein. The other 10 diets were formulated by 40% reduction in each EAA from the control diet which was replaced by a mixture of non-essential amino acids. Triplicate groups of fish were handfed with the experimental diets, three times a day to visual satiation. At the end of the experiment, the final body weight decreased in all EAA-deficient groups from 6.3% in fish fed arginine-deficient diet to 39.4% in fish fed lysine-deficient diet. According to the present results, the optimal balance of EAA in the diets for silvery-black porgy juveniles was (g 16g-1 N): arginine 5.28, lysine 5.96, threonine 5.20, histidine 2.54, isoleucine 4.58, leucine 5.36, methionine + cysteine 4.0 (in a diet containing 0.58 cysteine), phenylalanine + tyrosine 5.57 (in a diet containing 1.89 tyrosine), tryptophan 0.97 and valine 4.57.

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