Leech is a cold-blooded mollusk that can grow and reproduce in north and south China. It mainly lives in freshwater reservoirs, ditches, paddy fields, lakes and marshes, and most of them are in ponds with rich organic matter or small rivers without pollution. The optimum temperature for growth is 10-40℃. When the temperature is lower than 3℃ in the northern region, it enters the dormant hibernation period in the soil, and it stings activity above 8℃ from March to April of the following year. Leeches are omnivorous animals. They feed on animal blood or body fluids as their main way of life. They often feed on plankton, insects, and mollusks in the water. Under artificial conditions, they use various animal offal, cooked egg yolks, compound feed, and plant residues. Freshwater snails, shellfish, miscellaneous fish, and earthworms are used as bait.
