The amino acids composition of proteins from the whole fry fish, proteinic mass and the fish protein concentrate was investigated by using ion-exchange chromatography with an automatic analyzer (AAA-881, ChSSR). A balance of amino acids recorded during preparation of the protein mass obtained in fish with inferior market value (fry herring and sand fish) is cited. It was found that the protein mass of fry contains 2.3 and that of sand-fish, 1.3 as much of the amino acids as does the whole fish. It is methionine that has been ascertained to be a limiting amino acid for fry and the products of its processing. In the protein of this fish essential amino acids comprise 43.5% of the sum-total of all the amino acids, the corresponding percentages in the protein mass and the fish protein concentrate being 42.1 and 41.7, respectively. A comparison of the amino acids composition of the study proteins as against the amino acid scale of the ideal FAO protein shows that the protein mass and the fish protein concentrate represent products of high biological value.