The loach belongs to the class Ichthyosaurus and the family Loachidae. It is a warm-water fish with strong vitality. It likes to live in rice fields and ponds with water all year round. It has a wide variety of food habits and strong reproductive capacity. It inhabits the bottom of still water and humus silt, and likes to move at the bottom. It comes out to forage at night and feeds primarily on insects, snails, and aquatic plants, as well as humus. The loach has a thin intestinal wall, a straight intestinal tube, and many blood vessels. It can breathe. When there is a lack of oxygen in the water, it can also breathe through its intestines in addition to its gills. This phenomenon often occurs before sudden changes in climate and low-pressure rainstorms. In winter, when the water dries up and they dig into the mud, they can still survive by breathing through their intestines in a humid environment.

The suitable temperature for loach activities is 18℃～30℃. It grows fastest when the water temperature is 25°C to 28°C, and when it is above 30°C, it burrows into the mud bottom or grass to inhabit. Hibernation begins when the water temperature drops below 10°C. The following year, the water temperature rose by more than 5℃, and activities began. It grows vigorously from April to October. It likes to forage at night. All animals, plants, microorganisms and organic debris in water or mud are good food for it.

Loach and eel can be mixed together. The eel likes to move in the middle and upper layers of the water and survives by eating some molluscs such as earthworms, mealworms, maggots, and some swimming insects. The loach likes to move in the water. The middle and lower layers and bottom layer eat the excrement of some fish and insects for a living. In a precise sense, it is advantageous for loaches and eels to be mixed together. The remaining nutrients left by the eels can be digested by the loaches and the loaches clean the water.