Chai fish and Cai fish are two different kinds of fish. Chai fish, also known as black? ? Big black cheeks, big mouth? ? , is a large deep-sea fish. Living in deep-sea waters, it is black in appearance and has a special gill structure. Fortune fish, also known as snakehead, snakehead, grouper, raw fish, snakehead, dutiful son fish, moon fish and tripterygium wilfordii, is a common freshwater fish. Living in freshwater lakes, rivers and other waters, they have different appearance characteristics and ecological habits. They have similar names, but they belong to completely different fish.