Fish use the swim bladder to regulate buoyancy in the water, i.e. adjusting their relative weight to float without sinking or rising in the water. If the fish somehow gets an injury or disease to its swim bladder, regulating its buoyancy will be hard or impossible for the fish. A swim-bladder problem can therefore make the fish swim unnaturally and experience trouble keeping its buoyancy regulated. This can result in the fish laying on the bottom of the tank or floating on the surface. In less severe cases it can just seem like if the fish was drunk and having trouble keeping its balance. Swim bladder disease can be caused by a number of different causes but the most common causes are:
External factors: If the fish is subjected to external trauma it can affect their swim bladder. External trauma includes physical trauma such as being beaten by another fish, as well as rapid changes in the water parameters in their tank. A rapid temperature increase or decrease can as an example cause swim bladder disease.
Genetic factors: Some fish can be genetically predisposed to develop a deformed swim bladder when they grow older. This problem is usually a by product of line breeding by breeders trying to breed a certain trait in the fish such as long fins or certain colors. The predisposition is unwittingly being line breed along with the desired traits.
Cancer and TBC: Cancer and tuberculosis can cause swim bladder problems if they affect organs close to the swim bladder or the swim bladder itself.
Diet: Dietary problems such as poor nutrition can cause swim bladder disease as the fish don't get the nutrients they need. An improved diet can often help the fish recover, unless the problem has progressed too far. Poor diet can also lead to constipation which in turn can lead to swim bladder problem as the swelling of the abdomen prevent the swim bladder from working properly.
Diseases: Swim bladder disease can be a by-product of a number of different bacterial and parasitical infections in the fish.
The problem can usually be resolved by treating and resolving the problems listed above. Damages caused by external factors might be permanent and nothing to do about except kill the fish if it doesn't recuperate within a couple of weeks. You should also make sure that you give the fish their preferred environment if you discover swim bladder problems.
