The Amur grayling is a cold-water economic fish with extremely high aquaculture value

The Amur grayling belongs to the order Salmoniformes, family Thymallidae, genus Thymallus, commonly known as spotted trout and red-scaled fish. In China it is found in the upper reaches of the Heilongjiang River, the upper reaches of the Nenjiang River, the Mudanjiang River, the Ussuri River, the Songhua River, the Suifen River and other places. Abroad it is distributed along the coast of the Sea of Okhotsk and the coast of the Sea of Japan in Russia.

The grayling has two other subspecies in China: the Yalu River grayling from the Yalu River and the Arctic grayling from the **Irtysh River basin. The above three subspecies are quite similar in appearance and habits, differing only in geographical distribution.

The Amur grayling has an elongated and laterally compressed body, with a well-developed caudal peduncle. The snout is blunt and short. The mouth is terminal, with the upper and lower jaws equal in length. The mouth cleft is oblique. The upper jaw is free, and its end can reach below the vertical line through the center of the eye. The upper and lower jaws each have a row of fine teeth, and there are no teeth on the tongue. The eyes are large. The scales are small, with 80-98 lateral line scales, and the lateral line is straight. The dorsal fin is long and tall, with a rounded and convex upper margin, shaped like a flag; the adipose fin is small, located above and behind the origin of the anal fin; the dorsal fin and anal fin of females are larger than those of males. The back and sides of the body are purplish gray, and many small dark brown spots are scattered on the sides of the body; the color is obviously more vivid during the reproductive period, and adult fish have many large red spots on the sides of the body, with all fins reddish purple. There are 2 bands formed by reddish-brown spots on the dorsal fin. In addition to spots, juvenile fish also have several dark transverse bars on the sides of the body, which disappear as they grow. The abdomen is pale in color, and the overall body color is rather bright.

The Amur grayling is a cold-water fish and a typical fish inhabiting mountain streams in the northern cold temperate zone. Its range of movement is relatively small, and it does not enter large rivers and lakes throughout the year. In summer it mostly lives in the upper reaches of tributaries, preferring rivers with lush aquatic plants, abundant insects, clear water and relatively rapid flow; in winter it overwinters in the deep water of mountain streams and still does not stop feeding. Every year there is a short-distance spring migration for reproduction, suitable temperature and feeding, as well as an autumn migration to avoid drought and freezing. The grayling feeds mainly on invertebrates, mostly at night, and in summer it likes to feed in shallow water on aquatic insects and terrestrial insects that fall into the water. The age of maturity is 4 winters, and the breeding season is about mid-April to early May, when the parent fish gather in schools and swim into clear and swift currents to spawn, and the eggs often adhere to gravel on the riverbed.

The grayling has delicious flesh and is a valuable food fish, but its numbers are not large and no definite catch volume has been formed. Local fishermen mostly fish during the migration period, and the fishing intensity is too great, causing the already small resource stock to decline significantly. In addition, because reservoirs and water conservancy facilities are being built on the rivers, the spawning, feeding and overwintering environments of the grayling have been changed, which has also affected its reproduction and survival.