Amino acid composition of three species of Nigerian fish: Clarias anguillaris, Oreochromis niloticus and Cynoglossus senegalensis

An investigation into the concentrations of amino acids in three species of Nigerian fish: Clarias anguillaris, Oreochromis niloticus and Cynoglossus senegalensis was carried out. The most abundant amino acid was Glu (108–118 mg/g crude protein) and Leu was the most abundant essential amino acid (58.0–64.7 mg/g crude protein). While total amino acid content was 618–637 mg/g crude protein, the total essential amino acid content was 300–317 mg/g or 48.6–50.0% with His but 283–299 mg/g crude protein or 45.8–47.0% without His. The limiting amino acid was Thr for C. anguillaries and C. senegalensis but Val for O. niloticus whereas Phe + Tyr scores were greater than 1.0 (1.06–1.21) in all the fish samples. Significant differences existed between the contents of essential amino acids and non-essential amino acids at p < 0.05 in all the fish samples. Percentage contents of total neutral amino acids ranged from 52.2–54.9%; for total acidic amino acids the range was 26.9–29.6% and for total basic amino acids the range was 17.7–18.2%.