Swim Bladder Disorder in Aquarium Fish

Fish with this type of condition often have trouble floating

symptoms of swim bladder disorder
Illustration: Catherine Song. © The Spruce 2018

Swim bladder disorder refers to a collection of issues affecting the swim bladder, rather than a single disease. Although most commonly seen in goldfish and bettas, it can strike virtually any species of fish.

In this disorder, the swim bladder does not function normally due to disease, physical defects, or mechanical/environmental factors. Affected fish will exhibit problems with buoyancy, that is, they'll have difficulty floating.

Symptoms of Swim Bladder Disorder

Fish suffering from Swim bladder disorder exhibit a variety of symptoms that primarily involve buoyancy, including floating upside down, sinking to the bottom of the tank, standing on their head, or struggling to maintain a normal upright position.

Other physical signs such as a distended belly or curved back may also be present. Affected fish may eat normally, or have no appetite at all. If severe buoyancy problems exist, the fish may not be able to feed normally or even reach the surface of the water.

Causes of Swim Bladder Disorder

This disorder usually is caused by compression of the swim bladder. The most common cause of swim bladder compression is a distended stomach from rapidly eating, overeating or gulping air. Eating freeze-dried or dry flake food that expands when it becomes wet often leads to an enlarged stomach or intestine.

Low water temperature can slow the digestive process, which in turn can result in an enlarged intestine, that also puts pressure on the swim bladder.

Less common causes of compression of the swim bladder are other organs becoming enlarged. Cysts in the kidneys, fatty deposits in the liver, or egg binding in female fish can result in sufficient enlargement to affect the swim bladder.

Parasites or bacterial infections can inflame the swim bladder as well. Occasionally a hard blow from striking an object in the tank, a fight or fall can damage the swim bladder, causing problems that may be permanent.

Rarely fish are born with birth defects that affect the swim bladder, but in these cases, symptoms are present from an early age.

Treatment of Swim Bladder Disorder

Because an enlarged stomach or intestine is the most common cause of swim bladder disorder, the first course of action is to not feed the fish for three days. At the same time, increase the water temperature to 80 degrees and leave it there during the course of treatment.

On the fourth day, feed the fish cooked and skinned peas. Frozen peas are ideal for this, as they can be microwaved or boiled for a few seconds to thaw them, resulting in the proper consistency (not too soft but not too firm). Remove the skin, and then serve the pea to the fish. This course of action resolves many cases of swim bladder disorder.

While treating the fish, it often helps to reduce the water level to make it easier for the fish to move around within the tank. In tanks with a strong water current, it will help to reduce water flow while treating the fish.

If the affected fish floats with part of its body constantly exposed to the air, applying a bit of stress coat to the exposed area will help avoid development of sores. Hand feeding may be necessary if the fish has significant issues with movement.

If fasting and feeding peas do not relieve the problem, and the fish is having normal bowel movements, the problem is probably not due to an enlarged stomach or constipation. The fish may exhibit signs of infection such as clamped fins, shaking, and lack of appetite. Treatment with a broad-spectrum antibiotic may help in these cases (and for this, you'll need to visit your veterinarian).

When it is suspected the fish has swim bladder disorder due to a fall or injury, time is the only treatment. Keep the water clean and between 78 and 80 degrees and add a small amount of aquarium salt to the tank. If the fish does not recover and is unable to eat, the humane resolution may be euthanasia.

Prevention of Swim Bladder Disorder

Growing evidence indicates elevated nitrates may have a part in this ailment. It is well known that poor water conditions cause fish to be more susceptible to infections. Keeping the tank clean and performing regular water changes will go a long way towards preventing swim bladder disorder.

Keeping the water temperature a bit higher will help digestion, and possibly avoid constipation, another major cause of swim bladder problems.

Using high-quality foods will help, and soaking dried foods for a few minutes before feeding will help prevent constipation. Always thaw frozen foods thoroughly before feeding. For fish that frequently gulp air when feeding at the surface, try switching to sinking foods.

For all fish that have had a bout of swim bladder disorder, it's wise to cut back on overall feeding. Feed smaller portions so they can’t overeat.