Its most obvious features are its tall head and big eyes. Bigeye tuna is widely distributed in tropical and subtropical waters of the three major oceans, approximately between 40 degrees north and south latitude. The maximum body length can reach 200 cm and the weight can exceed 200 kg. The suitable water temperature range is between 10~15℃. The meat is bright red and soft, and the main sales market for the catch is the Japanese sashimi market. Taiwanese people call it big-eye tuna, scientific name: Thunnus obesus. It is distributed in the warm tropical zone and deep sea. The majority of big-eye tuna in Taiwan is caught in Donggang, and the rest are mostly caught in the deep sea.