The role of fish bubbles

Simply put, it is equivalent to a submarine.

The swim bladder, commonly known as fish bubble, contains air, which can make fish adjust their body density and float or sink in the water.

Most teleost fish that live in the upper and middle layers of seawater have swim bladders. The volume of swim bladder accounts for about 5% of the body. Its shapes are oval, conical, heart-shaped, horseshoe-shaped and so on. The gas filled in the swim bladder is mainly oxygen, ammonia and carbon dioxide, with the most oxygen content. Therefore, in an anoxic environment, the swim bladder can be used as an auxiliary respiratory organ to provide oxygen for fish.

The most important function of the swim bladder is to adjust the specific gravity of the fish by inflating and deflating, so as to adjust the water pressure balance inside and outside the bony fish and control the ups and downs of the body. In this way, when they swim, they only need a little strength to maintain a stable state in the water. The pressure of seawater increases with the increase of seawater depth, which is an obstacle for fish who want to visit the seabed. Therefore, when fish want to go down to the deep water layer, some gas will be discharged from the swim bladder, which will increase the proportion of fish and make it easier to dive. On the other hand, if you want to rise to a higher water layer, you should fill some gas to make the swim bladder swell. At this point, the density of the fish is less than the surrounding water, and the fish floats to the surface. The swim bladder allows bony fish to roam freely in the ocean.