What's the name of the white airbag in the fish's stomach? What role does it play in the life of fish?

The main purpose of the swim bladder is not breathing. Fish rely on the swim bladder to adjust their proportion. Through the swim bladder, they can slowly rise or fall without exercise. Most teleost fish have swim bladder as an organ to regulate buoyancy. The swim bladder was originally an expansion of the intestine. Some fish, such as the swim bladder of carp, are still connected with its intestine, while others, such as the swim bladder of perch, are completely separated from its intestine. If a fish wants to reduce its specific gravity, it will release dissolved gas in the blood into the swim bladder. Some fish use the oval shape in the swim bladder to inflate, while others use the intestine and the trachea connecting the intestine and the swim bladder. Similarly, fish can re-dissolve gas into the blood to increase their specific gravity. The swim bladder can also be used as a vocal organ.

Cartilaginous fish, some fish that live underwater and bony fish that swim fast, will sink to the bottom without swim bladder.

Protein, a biomacromolecule contained in swim bladder, is the raw material for human body to supplement and synthesize protein. Easy to absorb and utilize. It is stored in human tissues in the form of aqueous solution, thus improving the nutritional status of tissues and accelerating metabolism. It has been proved that foods rich in collagen can affect the physiological functions of some tissues through the binding water of collagen, thus promoting growth and development, enhancing disease resistance, delaying aging and resisting cancer.