The main area of the salmon is located in the southern part of the Sea of Okhotsk and the Sea of Japan basin. It is also found in rivers in the south of Kamchatka. Outwardly, Masu is similar to its relatives - coho salmon and chinook salmon, but differs from them by numerous spots on the sides, which cover not only the body, but also the fins of the fish. It has a powerful body covered with silver scales and a massive head with a large mouth. During the spawning period, the appearance of the Masu changes: at the base of the head grows a noticeable hump, and the lower jaw bends upwards and becomes hook-shaped. Teeth become larger. The body itself is covered with perpendicular cherry-coloured stripes. Adults can reach over a meter in length and 11 kg in weight.