How do fish maintain balance and buoyancy in water? " I know they have a swim blader that helps them to maintain some balance," but is their any thing else that helps them just as much.
The swim bladder is the main organ for buoyancy. Balance is generally maintaned with the pectorial fins. Ascending and decending in the water is also due to the pectorial fins acting like skis, although the other fins help to finetune all movements.
Infection on the air bladder is responsible for all the ailments where the fish keeps floating or sinking.