Most fish do not sink in water because of the presence of A)air sinuses B)buoyant scales on the body C)swim bladder D)swimmerets
Option C) Most fish are able to control their bouyancy with a swim bladder (an internal sac they can fill with gas or water) or by other means, so that they have a specific gravity exactly the same as the water they swim in. By small adjustments to their buoyancy, they can float to a higher level or sink lower with a very small expenditure of energy
