الفهرس 
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Abstract
The objective of this study is to extract the fish protein hydrolysate (FPH) by using three hydrolysis methods (chemical (C-FPH), enzymatic (E-FPH), and microbiological (M-FPH)) from Bigeye tuna waste (Thunnus obesus). The E-FPH and M-FPH techniques produced the highest yield, the greatest DH, the lowest average peptide chain length (PCL), the greatest caloric value, C-PER, and C-BV. In E-FPH, M-FPH, and C-FPH, the essential to non-essential amino acid ratios were 2.43, 1.79, and 0.51, respectively. The chemical score of E-FPH was the best in all of the amino acids recommended for adult humans, with Valine being the limiting amino acid, whereas a deficiency appeared in all of the amino acids recommended for Nile tilapia except Phenylalanine and Histidine, but it was supplied with high levels of needs. Protein and fat were also highest in the E-FPH and M-FPH hydrolyzed fish. Therefore, the E-FPH and M-FPH were used as partial substitutes (15% and 30%) for fish meal in diets for Nile tilapia fry, where the E-FPH diets 30% demonstrated significant differences (p < 0.05) than other treatments in some aspects of growth performance, proximate composition, protein and feed utilization parameters, but it was not superior to the control diet. Also, Nile tilapia fed on the E-FPH 30% diet had the highest muscle protein content (54.54%), lowest ether extract (18.45%), followed by E-FPH diets (15%), M-FPH diets (30%), and M-FPH diets (15%).