Why not salty sea fish?

Explaining the cause of non-salty marine fish

Fish living in seawater can be classified into two major types: hard bone fish and soft bone fish.

In the gills of hard bone fish, there is a special type of cell, called salt-producing cells. Salt-secreting cells can secrete salts, which can attract salt in the blood, after concentrating them into salts from the body along with viscous fluid. These salt-secreting cells always work with high efficiency, so the fish body keeps the salt content low.

The fact that soft-bone fish in seawater keep the body with low salt content is an ability. Usually in the blood of these fishes, there is a high concentration of urea, which makes the blood concentration higher than the sea level, thus reducing the penetration of salt content, so their meat is always not covered. now salty.