This study was aimed to compare the muscle lipid and protein composition of Oreochromis niloticus from five different localities in Egypt in order to determine the most nutritionally valuable samples based on the mode of feeding supplied. The fish samples were brought from the River Nile (natural feeding), Ismailia Canal (zooplankton feeding) and three fish aquacultures; Balteem (low protein diet, 18%),Al Abbasa (high protein diet, 30%) and Al Qanater Al Khaireya (zooplankton feeding in concrete tanks). Muscle total protein and total lipid contents were estimated. Fatty
acid and amino acid analysis were carried out. Studying muscle protein fractions was undertaken using SDS-PAGE electrophoresis. Results showed that the highest total proteins content was detected in the River Nile sample, while the lowest was estimated in Al Qanater fish sample. The percentage value of essential amino acids in the fish muscles from Al Abbasa was higher (45.6%) than the other four localities. Total lipids were found to have the highest value in Al Abbasa aquaculture sample whereas the lowest level was detected in the River Nile sample. Analysis of fatty acids and amino acids revealed variable differences between all the examined samples from the five localities.
Polyunsaturated fatty acid (PUFA) analysis showed that omega-3 had the highest % value in O. niloticus from the River Nile and Al Abbasa localities (30.30 and 30.36 respectively), while omega-6 fatty acids were higher in the fish samples from Balteem and Al Qanater (35.5% and 36.08% respectively) than the other fish samples. Elecrtophoretic data analysis showed that the highest number and percentage values of protein fractions among the five localities were recorded in sample obtained from the River Nile. It could be concluded that the best nutritional fish muscle quality was related to natural feeding in the River Nile sample and that fed on high protein diet at Al Abbasa aquaculture.