Abstract

The proximate composition, amino and fatty acids of four economically important fish species from the lagoons and off Lagos coast around Lagos, Nigeria were determined over a period of two years. The mean proximate composition of the freshwater species were 19.64% protein, 1.15% lipid, 76.71% moisture and 1.23% ash for Clarias gariepinus; 19.55% protein, 0.96% lipid, 76.75% moisture and 1.11% ash for Tilapia zillii. The mean proximate composition of the marine water species were 19.80%, protein, 0.40% lipid, 72.63% moisture and 1.13% ash for Pentanemus quinquarius and 19.86% protein, 1.06% lipid, 75.40% moisture and 1.17% ash for Pseudotolithus typus. Nine essential amino acids namely lysine, leucine, valine, isoleucine, threonine, phenylalanine, methionine, tryptophan and histidine that are very important for human health were present in all the species examined. The highest total amino acids value of 179.74 mgg^-1 was recorded in P. typus. The concentration of the total lipids, fatty acids, saturated, monounsaturated and polyunsaturated fatty acids levels were not the same within as well as between species. For the saturated fatty acids, palmitic acid had the highest proportion while oleic acid was the main monounsaturated fatty acid. Docosahexaenoic and eicosapentaenoic acids were the dominant polyunsaturated fatty acids in all the species. The results indicate that the fish species had high quality protein, essential amino acids and fatty acids. Overall, C. gariepinus appears to be the best diet for its relatively high nutrient components and the ratio of polyunsaturated: saturated fatty acid is followed by P. typus, P. quinquarius and T. zillii.

Key words: Proximate, freshwater, marine, fatty acids, amino acids, Nigeria.