The living habits and morphological characteristics of the two-branched fish Tetrabranchial Fish

Gyrinocheilus aymonieri, also known as Gyrinocheilus aymonieri, is a fish with four gills. It belongs to the order Cypriniformes, family Dipsidae, and genus Dipsus. Commonly known as: double-hole fish, algae-eating fish. English name: Biforated carp, Double galopening carp.

Endangerment level: Endangered.

The body is cylindrical, with a flat tail and a round abdomen. The head is broad and slightly flat. The muzzle is blunt and round, with an arc-shaped depression on the back. The mouth is small and located downward. The snout extends ventrally and is not separated from the upper lip. It is connected with the lower lip at the corner of the mouth to form a complete funnel-shaped mouth sucker. There are multiple rows of papillae on the inside of the snout, and there are also multiple rows on the inside and outside of the lower lip. Mastoid. The anterior edge of the mandible is horny, with a small ventral opening and a longitudinal valve dividing it into two. The posterior labial sulcus is discontinuous. The eyes are small and located at the back of the head. With two pairs of gill openings. No pharyngeal teeth or whiskers. Lateral line scales 40-41. The starting point of the dorsal fin is at the midpoint of the starting points of the pectoral and pelvic fins; the even fins and anal fins are both small; the caudal fin is forked. The back of the body is gray-black, the belly is white, and there are 8-9 black spots on the back and sides, sometimes in 2 rows. The tail fin has dotted stripes, and the other fins are gray.

It likes to live in rivers with rocky bottoms in mountainous areas, mostly in rapids of mountain streams, and can live in still water. The mouth is adsorbed on the surface of stones or other objects, and water enters through the water inlet hole for gas exchange, and then is discharged through the gill pores, replacing the opening and closing of the mouth. It breathes 230-240 times per minute, far more than other fish. Feeds on algae, plant debris, etc. They lay eggs in streams from June to July when the river water surges.

Domestically, it is only distributed in Menghai and Mengla (belonging to the Lancang River system) in Xishuangbanna, Yunnan; abroad it is distributed in the Mekong River system.

The fish is not very large, with an average body length of 100-150 mm. The quantity has always been rare, and now it can be seen occasionally in the place of origin. The habitat of Dipsus is single and its adaptability is poor, so its population is small. There are only 2-3 species of the genus Dipsus in the Indo-China Peninsula and only 1 species in my country. It has certain scientific research value in fish taxonomy and comparative anatomy, and is a precious specimen in teaching and scientific research. In addition, fishermen along the river mostly catch it during the spawning season, so the number has dropped sharply and is on the verge of extinction.

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