0 an organ like a bag inside a fish that holds air so that it does not sink and stays in the correct position -- （鱼的）鳔
The gills, liver, spleen, heart, gonads and swim bladder were all removed and examined for parasites.
Squashed preparations of visceral organs, including heart, liver, spleen, kidney, gall bladder, swim bladder and gonads, were made and examined under a light microscope.
This differs from the method of flotation used by most fish, which involves a gas-filled swim bladder.
Gar and bowfin have a vascularized swim bladder that functions in the same way.
In lungfishes, bowfin and bichirs, the swim bladder is supplied with blood by paired pulmonary arteries branching off from the hindmost (6th) aortic arch.
The swim bladder is evolutionarily homologous to the lungs.
It is advised to feed goldfish only sinking food because flakes can cause swim bladder issues.
Since the shallows were subject to occasional oxygen deficiency, the ability to breath atmospheric air with the swim bladder became increasingly important.
