Swim Bladder Disorder in Aquarium Fish

Fish with this type of condition often inappropriately float or sink

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 commonly seen in goldfish and bettas, it can strike virtually any species of fish.

What Is Swim Bladder Disorder?

Swim bladder disorder refers to a condition when the swim bladder does not function normally due to disease, physical abnormalities, mechanical/environmental factors, or for reasons that cannot be diagnosed. Affected fish will exhibit problems with buoyancy, that is, they'll have difficulty controlling their ability to float or sink.

Symptoms of Swim Bladder Disorder

Fish suffering from swim bladder disorder exhibit a variety of symptoms that primarily involve buoyancy, including sinking to the bottom or floating at the top of the tank, floating upside down or on their sides, or struggling to maintain a normal 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 is sometimes caused by compression of the swim bladder, which may involve a distended stomach from rapidly eating, overeating, constipation, or gulping air, which is thought to occur with floating foods. Eating freeze-dried or dry flake food that expands when it becomes wet can also lead to an enlarged stomach or intestinal tract.

  • Low water temperature can slow the digestive process, which in turn can result in gastrointestinal tract enlargement that puts pressure on the swim bladder.
  • Other abdominal organs may become enlarged and affect the swim bladder. 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.
  • Rarely fish are born with birth defects that affect the swim bladder, but in these cases, symptoms are usually present at an early age.

Treatment

If an enlarged stomach or intestine is thought to be the cause of a 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 78-80 degrees Fahrenheit and leave it there during treatment.

On the fourth day, feed the fish a cooked and skinned pea. 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. You can continue to feed a pea a day for a few days and then switch to a species-appropriate food, but avoid flakes or pellets that float.

If an infection is thought to be the cause of a fish's swim bladder disorder, treatment with a broad-spectrum antibiotic may help, and for this, you'll need to visit your veterinarian.

Other supportive treatments (regardless of the cause) can include:

  • Keeping the water especially clean and between 78 and 80 degrees Fahrenheit
  • Adding a small amount of aquarium salt to the tank
  • Reducing the water level to make it easier for the fish to move around within the tank
  • Reducing water flow in tanks with a strong current
  • 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 may help avoid the development of sores
  • Hand feeding may be necessary if the fish has significant issues with movement

Unfortunately, many cases of swim bladder disorder do not respond to treatment. If the fish does not recover in a reasonable period, the humane resolution may be euthanasia.

How to Prevent Swim Bladder Disorder

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 can help prevent swim bladder disorder.

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

Feed only high-quality foods, and consider soaking dried foods for a few minutes before feeding. Always thaw frozen foods thoroughly before placing them in the tank. For fish that gulp air when feeding at the surface, try switching to sinking foods.

Avoid over-feeding at all costs. Feed smaller portions so fish can’t overeat and watch the total amount you feed throughout the week.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.