Bony fish
Bony fish also possess an organ called a swim bladder which can alter the buoyancy to maintain or adjust their position in the water.
The bony fish had to go and relieve its bladder.
Swim bladder gas
Most bony fish have a swim bladder which controls their buoyancy (the depth at which they settle in the water). Some fish get gas into their swim bladders by surface gulping. Others fill the swim bladder with gases, mainly oxygen, from the blood. The oxygen is taken into the blood via the gills.
