According to the description of the subject may be red-tailed loach.

Red-tailed loach, fish, belongs to the carp order, loach family, loach genus. Distributed in the headwaters of the tributaries of the Han River, as well as the plug river, the Yangtze River tributaries along the river, Jinsha River, Nanpanjiang River, Weihe River system and so on. Small fish, body length is generally 10~17cm, benthic life, like to live in the environment of the rocky caves washed by flowing water, generally more in mountain tributaries, when the flood came to swim out to feed on the bait brought by the flood. Normally, it likes to perch in rock crevices, stone gaps or backwater bays with many boulders.

Dorsal fin Ⅲ~8~9; anal fin Ⅱ~5; ventral fin Ⅰ~6; pectoral fin Ⅰ~9. Vertebrae 4 x 42 a 44. Body length is 7.8~8.8 times of the height, 4.7~5.6 times of the head length, 4.7~5.4 times of the caudal peduncle length. 10.0 to 10.8 times as long as height of caudal peduncle. Head length 2.5 times as long as muzzle length, 7.5 to 10.0 times as long as eye diameter, 4.0 to 4.2 times as long as eye spacing. Caudal peduncle 1.9 to 2.3 times as long as height of caudal peduncle.

Body elongate, anterior segment rounded, caudal peduncle laterally compressed. Snout conical. Eyes small, laterally superior. Mouth inferior, stomodeum arcuate. Whiskers 3 pairs, moderately long. Gill pores small. Lateral line complete. Upper and lower margins of caudal peduncle with well-developed skinfold ribs. The dorsal fin is small, the pectoral fins are low positioned and oval, the ventral fin begins slightly behind the beginning of the dorsal fin, the anal fin is small, and the caudal fin is rounded with a slightly concave center.

Dorsal surface is grayish brown, mixed with a regular mottled pattern, lateral side of the body is yellowish brown with 15~17 dark brown stripes, those on the posterior part of the body are more obvious than those on the anterior part, ventral surface is light yellow, caudal fin is bright red, and all other fins are light yellow.

The anterior half of the body is naked and scale-free, and the posterior half is finely scaled. Maxillary center with a tooth-like protuberance. There are 3 pairs of whiskers. The dorsal fin is located in the anterior half of the body, and the anterior distance of the dorsal fin is 43.5-47% of the body length. The beginning of the ventral fin is opposite to the beginning of the dorsal fin or located at the first root of the dorsal fin.

The red-tailed loach is usually found in rock crevices, rock gaps or migratory boulder-filled bays. It often scrapes food on rocks with the well-developed horny edges of the lower jaw. However, it is still the insect larvae (larvae of Mayfly, Megaloptera, Coleoptera, etc.) that appear more food in the intestinal tube. Its individuals are small but the natural population in the production area is large, and its meat is tender, making it a common small food fish in the region.

The red-tailed loach is a small benthic fish that prefers clusters and often lives in mountain streams, rivers with clear, unpolluted water and sand or gravel. In the process of domestication, the fish often gather under the concealment, afraid of light, and mostly active at night.

The red-tailed paracobitis (Paracobitis variegtus) is widely distributed in the upper reaches of the Yellow River, Yangtze River, and Nanpanjiang River systems. Characteristics such as the number of dorsal fin branches, the morphology of the anterior nostrils, the head markings, the length of the whiskers, and the degree of scaling on the forebody indicate that the Paracobitis variegtus has been divided into two subspecies.

The distributions of the two subspecies are geographically isolated from each other: the distribution of the named subspecies of the red-tailed loach, P. variegatus variegatus, is restricted to the upper reaches of the Yellow and Yangtze River systems, while the new subspecies of the long-finned loach, P. variegatus longidorsalis, is only found in the upper reaches of the Nanpan River. The divergence of subspecies may be related to the dramatic uplift of the East Yunnan Plateau during the Late Pleistocene.