Tuna: It is a group of marine fish belonging to Sparidae, Sparidae and teleost. This family contains 5 genera 15 species of tuna, and the size of each species varies greatly. The smallest tuna is Coilia oleifera, the largest is 50 cm long and weighs 1.8 kg. The largest tuna is Atlantic bluefin tuna, with a maximum length of 4.6 meters, a weight of 684 kilograms and an average body length of 2 meters. It is thought that its life span can be as long as 50 years. Tuna is tapered at both ends, with a moderate mouth and well-developed teeth. The branchial membrane is not attached to the pharyngeal isthmus. Scales are cycloidal, usually small, and their body color is metallic, usually blue and silver. Tuna has dark stripes and fins. The dorsal fin consists of 9 ~ 27 closely arranged fins, and the ventral fin has 6 fins.