Black herring is inactive and usually lives in the middle and lower layers of water. Its food is mainly snails, clams, clams and so on. It also preys on shrimp and insect larvae. In the fry stage, they mainly feed on zooplankton. Black herring grows rapidly, and the individual is large, and the largest individual of adult fish can reach 70 kg. Crabs, also known as river crabs and hairy crabs, belong to benthic crustaceans and are easily swallowed by other carnivorous fish, frogs and waterfowl. During the shelling. The Chinese mitten-handed crab breeding base suggested that a small amount of silver carp could be mixed in the crab pond, and other fish should not be mixed as much as possible.