Scale fish generally refers to smelt.

Smelt (scientific name: Osmerus mordax) is a fish of the family Smeltidae and the genus Smelt. Smelt is a deep-sea fish native to Japan. Because there are many fish eggs in the belly of the female fish, it is named "Duochun" (in southern Chinese dialects such as Hakka, "egg" and "egg" are called "spring") . Therefore, it is also called spring fish and capelin. The English name is smell, and the Russian name is снеток. The body length is no more than 3 inches (about 7.6cm), the body is flat on the long side, the scales are small, and the lateral line is incomplete. The snout of the smelt is located at the end, the mouth slit is larger, and the eyes are also larger. The diameter of the eyes is roughly equal to the length of the snout. The dorsal fin of the smelt is higher, but the caudal fin is very thin and the caudal fin is deeply forked. The smelt has large canine teeth on its tongue, and the end of the maxilla extends beyond the posterior edge of the pupil. Distributed in the North Atlantic and Northwest Pacific. It is produced in Heilongjiang and Tumen River in my country. Middle and pelagic omnivorous fish. Young fish feed on rotifers and cataphim. They usually live in the sea and live in groups.