1, true loach: generally known as the mud loach. 2, the body is long cylindrical, the tail is laterally compressed, the mouth is inferior, horseshoe-shaped, and the lower part of the body side is white or light yellow. 3, the large-scaled paralichthys olivaceus loach: distributed in the middle and lower reaches of the Yangtze River and its subsidiary bodies of water. 4, the body is like the mud loach, the whiskers are five pairs, the caudal fins are rounded, the anus is close to the start of the buttocks. 5, the Chinese sand loach: distributed in the middle and upper reaches of the Yangtze River, also known as the steel loach, the kiss is long and pointed, lives in the slow water areas of gravel bottom rivers. Long and pointed, three pairs of whiskers, living in the gravel-bottomed river section of the slow-water area, often in the bottom of the activities.

I. True loach

Generally known as loach. The body is long cylindrical, the tail is laterally compressed, the mouth is inferior, horseshoe-shaped. Mouth whiskers 5 pairs, 3 pairs of maxillary, relatively large, 2 pairs of mandibular, a small one. The caudal fin is rounded and the scales are tiny and buried under the skin. The back and dorsal part of the body is grayish black with small black spots. The lower part of the side of the body is white or light yellow with black spots on the upper part of the base of the caudal peduncle. The body has a lot of mucus, the head is pointed, the muzzle protrudes in front, and the eyes and mouth are small.

Two, large-scaled loach

Distributed in the middle and lower reaches of the Yangtze River and its subsidiary water bodies. Body like loach, whiskers are five pairs. The eyes are covered by the dermal membrane. No subocular spines. Scales are large and buried under the skin. The caudal peduncle is bordered by skin folds and is connected to the caudal fin. The length of the caudal peduncle is equal to its height. Caudal fin is rounded. The anus is near the beginning of the anal region.

Three, Chinese sand loach

Distributed in the middle and upper reaches of the Yangtze River. It is also known as steel loach. The muzzle is long and pointed. The whiskers are three pairs. There is one pair of knob-like protrusions under the chin. The subocular spines are forked and end beyond the posterior margin of the eye. There are no scales on the cheeks. Anus near the beginning of the buttocks. Caudal peduncle low. Lives in slow-water areas of gravel-bottomed reaches, often on the bottom.