From the point of view of its distribution waters, tuna is a kind of marine fish, not a freshwater fish. In addition, from the point of view of their distribution waters, the main distribution waters are between 100-400 meters deep. Generally speaking, fish distributed at depths of more than 200 meters can be called deep-water fish, so many species of tuna belong to deep-water fish.
Specifically, the distribution depth of different species of tuna is also different, some are distributed in deeper areas, while others are distributed in shallower areas. Even for the same kind of tuna, their distribution of water depth is also different. For example, "bluefin tuna" species live in some very deep places, while others live in relatively shallow places, may only be about 50 meters from the surface of the water. For example, the distribution of "bigeye tuna" species may be slightly deeper, mainly in 200-300 meters of water depth, a few in the surface.
As mentioned above, tuna's distribution waters are concentrated in 100-400 meters, which can be counted as deep-water fish. However, the specific distribution depth of different species is different, and some tuna of the same species live in shallower areas, while others live in deeper areas. However, there is one thing in common, they can not live in too shallow water, because their body structure has adapted to the deep ocean environment, that is, the environment with higher pressure. If they suddenly live in shallow water, there will be some problems due to changes in pressure, and sometimes even lead to the rupture of their internal organs.
