1 Crayfish was introduced from Japan in 1930s and 1940s, and Japan introduced from the United States earlier, mainly used as food and pets. Crawfish are often mixed in crop fields. There is no need for artificial incubation. Once the original seed is put into the pond, it can achieve self-maintenance. After harvesting, it is not necessary to put the original seed again. Escaped individuals dug holes in the dam to survive.

2. It can survive in temporary water bodies, and it has a wide range of feeding habits, and it is extremely fast to establish a population and easy to spread. Extremely threatening local fish, crustaceans and aquatic plants, destroying the local food chain; Because it feeds on roots, it directly damages crops (especially aquatic and semi-aquatic crops such as rice) and natural vegetation.