1. Albacore tuna is spindle-shaped, plump and smooth. Its main feature is that the first dorsal fin is dark yellow and the second dorsal fin is light yellow. The back has a dark blue metallic luster, and the edges and abdomen are silvery white, which belongs to pelagic migratory fish.
2. Southern bluefin tuna is fat and spindle-shaped, with a body length of more than 2m and a weight of more than 200kg, and its back is dark blue. The color of the abdomen is silver, but there may be no color on the larger adult fish.
3. Big-eyed tuna has a thick spindle shape, a short tail, a blue-blue back and a gray abdomen. It mainly gathers in the waters near the equator and likes to swim in groups, belonging to pelagic migratory fish.
The remaining species
1. Generally, the bluefin tuna is 30-40cm long and weighs 1.5-2kg. Mainly living in the waters with clear water and sandy rocks or coral reefs at the bottom. Sensitive to temperature, salinity and water color changes, it belongs to slow-swimming pelagic fish.
2. Blackfin tuna likes clean water and warm environment, and often lives in the sea where the water temperature is above 20℃, belonging to oceanic pelagic fish.
3. The habitat of yellowfin tuna is limited by water temperature, and it is often concentrated in the waters with surface water temperature of 20-28℃. The water layer is shallow in summer and deep in winter, belonging to pelagic migratory fish.