The loach is a fish.

The loach is a small demersal fish that lives in static or slow-flowing water on silty bottoms, and is adaptable enough to live in humus-rich environments. Loach has gills, usually in the water is to use the gills to breathe, just when the oxygen content of the water is not enough will float to the surface of the open mouth to swallow the air, through the oral mucosa respiration.

We see the loach after leaving the water is still not dead, that is because the loach skin can secrete mucus, keep the skin moist, so you can breathe through the skin. So the loach has three ways of breathing, gill breathing, oral breathing and skin breathing, but mainly gill breathing, the other two just as a kind of auxiliary breathing.

Types of loach

1, true loach

Body is long cylindrical, the tail is laterally compressed, the mouth is inferior, horseshoe-shaped. There are 5 pairs of mouth whiskers, 3 pairs of upper jaws, which are larger, and 2 pairs of lower jaws, one large and one small. The caudal fin is rounded, and the scales are tiny and buried under the skin. The dorsal and dorsal side of the body is gray-black with small black spots. The lower half of the body is white or light yellow, with a large black spot above the base of the caudal peduncle. There is more mucus on the body surface, the head is pointed, the muzzle protrudes forward, and the eyes and mouth are small.

2, large-scaled loach

Distributed in the middle and lower reaches of the Yangtze River and its subsidiary bodies of water, the body shape is similar to the loach, whiskers 5 pairs. The eyes are covered by the dermal membrane, without subocular spines. The scales are large and buried under the skin. The caudal peduncle has well-developed folds and ribs, which are connected with the caudal fin. The caudal peduncle is about equal in length and height, the caudal fin is rounded, and the anus is near the beginning of the brachial fin.

3. Zhonghua Sha Loach

Distributed in the middle and upper reaches of the Yangtze River, it is also known as steel loach. The snout is long and pointed, with 3 pairs of whiskers. There is 1 pair of knob-like protuberances under the chin, and the subocular spines are forked, with the ends exceeding the posterior margin of the eyes. The cheeks are not scaly, and the anus is near the beginning of the anal fin. Tail machine is low, inhabiting slow-water areas of gravel-bottomed reaches, often on the bottom.