A Comparative Study of Amino Acids in the Muscle of Different Species of Fish

1. The complete amino acid composition in the muscles of ten common food fishes has been investigated by microbiological methods. Each amino acid was determined simultaneously in all samples, thus making a direct comparison of the contents in the different species possible. 2. The amino acid percentages of the protein (N x 6.25) were essentially the same in the muscle of the different fishes. The only exception was the value for histidine in mackerel, which was twice as high as the contents found in the remaining nine species. 3. The present values were generally of the same order as the averages of the data in the literature. 4. The total amino acid nitrogen compared with the total nitrogen of the samples, made it possible to calculate more exact conversion factors for the estimation of protein in fish muscle. This proble1n has been discussed. 5. Compared with FAO's "provisional pattern" for the nutritional requirement, tryptophan was the first limiting amino acid followed by the sulphur containing amino acid. Compared with BENDER's "target values", the sulphur containing amino acids were the only limiting factors