The present study was conducted to determine the chemical composition and nutritional quality of 10 commonly consumed fish species (kingfish, yellowfin tuna, longtail tuna, sharks, emperor, grouper, yellowfin goatfish, sardine, Indian mackerel, and sea bream) in Oman. Five representative samples of each specie were procured from the local fish market in Muscat during the two seasons in summer (June) and autumn (September), 2005. The fish samples were processed for determining the condition factor (k), flesh percentage, proximate chemical composition, as well as for fatty acids and mineral contents. Significant (p < 0.05) differences were observed in the condition factor, flesh percentage, and proximate chemical composition of different fish species. Seasonal variability however only affected the moisture, ash and fat contents but not the protein content of fish. Kingfish and shark showed lower condition factor (0.5) whereas yellowfin tuna, emperor and yellowfin goatfish showed higher condition factor (1.4). Grouper showed the lowest flesh percentage (31.7%) while kingfish showed the highest flesh percentage (71.5%). The moisture, ash, total fat, crude protein contents and energy values of various fish species ranged between 67.0-78.2%, 1.1-1.5%, 0.6-6.2%, 19.1-26.1%, and 86-136 kcal/100g of fish flesh respectively. Twenty different fatty acids were identified in these fish species, which differed significantly (P«< 0.05) among various fish species. The seasonal variability affected (P<0.05) the total saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) but did not affect the total polyunsaturated fatty acids (PUFA) contents. However, the seasons*species interactions were significant (P<0.05). The highest concentration of fatty acids was observed for saturated fatty acids (SFA), followed by monounsaturated (MUFA), and polyunsaturated fatty acids (PUFA) respectively. Shark and sea bream showed the lowest SFA content (0.3%), whereas sardine showed the highest SFA content (2.9%). Sixteen important minerals of nutritional significance were determined in these fish species. Significant (P <0.05) differences were also observed in the mineral composition of various fish species. 1 variability however did not affect the mineral composition of fishes. The results of the present study indicated that significant variability exists in the nutrient composition of various fish species however; the seasonal variability affected the moisture, ash and total fat, SFA and MUFA but not the protein, PUFA and mineral contents of fishes. It may be concluded that commonly consumed fishes in Oman represent an excellent source of protein, essential fatty acids and important minerals and should remain a regular part of Omani diet.