No, I keep saying it, so I have to mention it. Crayfish, scientific name crayfish, originated in the United States, is one of many crayfish in the United States. It was really introduced into China by Japanese during World War II. Because crayfish is omnivorous and adaptable, it is only a kind of crayfish with strong adaptability, and it does not have the so-called ability to purify sewage on the Internet, and heavy metals may seriously exceed the standard. It can't survive in that environment. The head of shrimp is where the internal organs of shrimp are, so eat shrimp without eating the head. Spot checks on crayfish show that only a few head metals are slightly higher than the index. If there were rumors on the Internet, the country would have banned them. Crayfish is omnivorous and warm, and can turn over in anoxic water and breathe in the air. The status of crayfish in shrimp is equivalent to that of carp and crucian carp in freshwater fish in China, so it has strong adaptability.