Hairtail (scientific name: Trichiurus lepturus) belongs to trichiuridae, a perciformes of bony fishes in the subphylum Vertebrates of Chordata. Also known as nepotism, fat belt, oil belt, toothfish, etc., it is fierce. Qingdao and Rizhao cities along the Yellow Sea are called snakeheads. Hairtail's body shape is flat like a belt, silvery gray, dorsal fin and pectoral fin are light gray with tiny spots, tail is black, the tip of hairtail is big, and it gradually tapers to the tail, with a total length of about 1 meter. It is fierce and mainly feeds on shrimps and squid. It is mainly distributed in the western Pacific Ocean and Indian Ocean, and distributed in the Yellow Sea, East China Sea, Bohai Sea and South China Sea in China. It is also known as the four major seafood in China with large yellow croaker, small yellow croaker and squid.