Fatty acid composition and amino acid profile of two freshwater species, African catfish (Clarias gariepinus) and tilapia (Tilapia zillii).

The proximate, fatty and amino acids composition of two commercially important freshwater fish species Clarias gariepinus and Tilapia zillii. purchased from local fishermen in two landing sites in Lagos State, Nigeria were determined. Live specimens of C. gariepinus were purchased while samples of T. zillii were stored in an ice chest at 40C and conveyed to the laboratory for analyses. The chemical composition of the samples was determined using AOAC methods. The protein content of C. gariepinus and T. zillii was 18.8% and 19.0% (% wet weight), respectively. The total lipid content was high for C. gariepinus (9.3%) but low for T. zillii (1.1) %. Lipid composition varied in the two species but differences were not statistically significant (P>0.05). The ash was 1.2% for both species. The moisture content was higher in T. zillii (80.4%) than in C. gariepinus (74.3%). The percentage composition of individual fatty acids as a ratio of total muscle lipids of C. gariepinus ranged from 0.1% to 26.0% and that of T. zillii from 0.1% to 32.2%. Among them, those occurring in the highest proportions were myristic acid (C14:0, 4.2-5.2%), palmitic acid (C16: 0, 22.0-32.2%), palmitoleic acid (C16:1, 3.6-13.2%), heptadecanoic acid (C17:0, 0.7-3.0%), stearic acid (C18:0, 8.1-9.5%), linoleic acid (C18:2, 1.4-12.3%) and oleic acid (C18:1). Amino acids from sample protein in C. gariepinus ranged from 0.30% to 17.81% and that of T.zillii from 0.27% to 18.16%. The most abundant amino acids in the two fish species were glutamic acid, aspartic acid, leucine and lysine ranging from 9.49% to 18.16%. The ratio of ω3/ω6 fatty acids was less than 1 in C. gariepinus while in T. zillii it was 2.70. The two freshwater fish species contain essential fatty acids particularly eicosapentaenoic acids and docosahexaenoic acids and essential amino acids for promoting good health, prevention and healing of diseases in humans. The two freshwater fish were therefore found to be important sources of nutrients. Keywords: Proximate, Freshwater, fish, fattyacids, aminoacids. AJFAND Vol. 9 (1) 2009: pp. 609-62