The living habits and morphological characteristics of rat fish (big-eyed crocodile)

Ptychidio macrops (Ptychidio macrops) belongs to the order Cypriniformes, family Cyprinidae, subfamily Ptychidio, and genus Ptychidio macrops. Commonly known as: square head, deep-eyed fish, oily fish. English name: Rat-mouth barbel, Bigeye ratmouth barbel.

Endangerment level: Endangered.

The body is cylindrical, with a bulge behind the head, a straight ventral surface, and a thick and short tail peduncle. The head is short and broad. The muzzle is round and blunt, with lateral channels leading to the corners of the mouth. The middle part of the snout is covered under the skin, and the edges are arranged in more than 10 tassels with side branches. The tassels are short and have many small cone-shaped papillae at their base. There are many short whisker-like protrusions on the edge and ventral surface of the lower lip. The mouth is small, inferior and in the shape of "∏". The upper jaw is pointed and separated from the snout; the lower jaw is round and separated from the lower lip; the edges of the upper and lower jaws are both well-developed horny. There are 2 pairs of barbels, short; the muzzle barbels are longer, with the end reaching the edge of the eye at most. Big eyes. The lateral line is flat and has 37-41 lateral line scales. The dorsal fin has no hard spines and its origin is near the snout; the anal fin is long. The body is dark green, the back and head are dark, the abdomen is white, and each fin is gray.

They mostly live in clear water bodies with stony gravel substrate. The individuals are small, with common individuals weighing around 100 grams.

The distribution area is narrow, only in parts of Zuojiang, Yongjiang and Liujiang rivers in the Xijiang River system. It is rare in number and was only discovered in the 1980s. It is a rare species. This fish is selective about habitat conditions, and individuals living within the production area are affected by changes in environmental factors such as hydrology, which is very detrimental to its growth and reproduction.

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