Fish bubble fish bubble is also known as fish swim bladder. The swim bladder is commonly known as fish bubble. It contains air, which can make the fish adjust the density of the body and rise or sink in the water. Most bony fishes that live in the upper and middle layers of the sea have swim bladder. The size of the swim bladder is about 5% of the body. Its shapes are oval, cone, heart, horseshoe 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 oxygen-deficient environment, the swim bladder can be used as an auxiliary respiratory organ to provide oxygen to the fish. The dried product of fresh and high-quality fish maw (commonly known as fish bladder) is a traditional seafood food, known for its viscous substance, so people also call it fish glue and fish glue .