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Swim Bladder Disease and Treatment in Aquarium Fish

goldfish in aquarium

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Swim bladder disease is a condition that occurs when a fish's swim bladder isn't working properly. The swim bladder is a gas-filled internal organ that helps bony fish maintain buoyancy. The disorder refers to a collection of issues affecting the swim bladder, rather than a single disease. Although commonly seen in goldfish and bettas, swim bladder disease can affect virtually any species of fish. The disorder is often treatable, and a fish can experience a full recovery. Here's what you need to know about swim bladder disease in fish.

What Is Swim Bladder Disease?

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

Symptoms of Swim Bladder Disease in Aquarium Fish

Sometimes a fish owner may think fish floating abnormally in the tank are dead, but they may actually be exhibiting symptoms of swim bladder disease. Fish suffering from swim bladder disease exhibit a variety of symptoms that primarily involve buoyancy.

Sinking or Floating to the Top

If the swim bladder is deflated, it will sink in the tank. If the fish has gulped in too much air while feeding, this may cause it to float to the top of the tank.

Struggling To Stay Upright, Swimming Upside Down or Sideways

A fish that does not have buoyancy problems tends to remain static and upright in the water. If your fish are struggling to stay upright—or swimming sideways or upside down—you will see excessive fin movement they're using to try to float the right way.

Distended Belly

Compression of the swim bladder may cause a the fish to swim with a distended stomach. The fish's digestive process may become disrupted with this disorder, which may cause the belly to become enlarged.

Curved Back

If the fish's abdomen is inflated, other organs are pushed aside which can sometimes cause the spine to curve.

Changed Appetite

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.

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Causes of Swim Bladder Disease

This disorder can be caused by many issues, spanning from environmental to feeding problems, including the following:

  • Rapidly eating, overeating, constipation, or gulping air may occur with floating foods to cause an extended belly and displace the swim bladder. Eating freeze-dried or dry flake food that expands when it becomes wet can also lead to an enlarged stomach or intestinal tract.
  • 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.
  • Low water temperature can slow the digestive process, which in turn can result in gastrointestinal tract enlargement that puts pressure on 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 a fall can damage the swim bladder.
  • Though rare, some fish are born with birth defects that affect the swim bladder. Symptoms are usually present at an early age.

How Vets Diagnose Swim Bladder Disease in Fish

Typically, swim bladder disease is diagnosed at home by the observation of symptoms. However, an X-ray is the only way to confirm a swim bladder diagnosis. For this, you can bring your fish to a veterinarian specializing in aquatic conditions. An X-ray will show the swim bladder's size, shape, and location. It can reveal fluid or other abnormalities inside the bladder, such as another growth or disease that is pushing on or displacing the bladder.

To find a fish veterinarian near you, check out:

Swim Bladder Disease Treatment

Treatment of swim bladder disease in fish involves water maintenance, feeding changes, and possible antibiotics.

  • Let the fish fast: If an enlarged stomach or intestine is thought to be the cause of a swim bladder disease, the first course of action is to not feed the fish for three days.
  • Fix the water temperature: At the same time the fish is fasting, increase the water temperature to 78-80 degrees Fahrenheit and leave it there during treatment.
  • Feed the fish peas: 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 one pea a day for a few days and then switch to a species-appropriate food but avoid flakes or pellets that float.
  • Antibiotics: If an infection is thought to be the cause of a fish's swim bladder disease, treatment with a broad-spectrum antibiotic may help. For this, you'll need to visit a fish veterinarian.

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

  • Keep the water especially clean and temperatures between 78 and 80 degrees Fahrenheit.
  • Add a small amount of aquarium salt to the tank.
  • Reduce the water level to make it easier for the fish to move around within the tank.
  • Reduce 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 water conditioner (which helps improve the fish's slime coat) can help avoid the development of sores and reddened spots.

Prognosis for Aquarium Fish With Swim Bladder Disease

Sometimes, a swim bladder disease is only a temporary condition that responds to treatment. Fish with this disorder will have a problem eating, which can be fatal, so you may need to hand-feed your fish if it has significant issues with movement. Unfortunately, some cases of swim bladder disease will not respond to any type of treatment. If the fish does not recover within about one or two weeks of treatment, the humane resolution may be euthanasia. An aquatic veterinarian can advise you on the best course of action.

How to Prevent Swim Bladder Disease

It's well known that poor water conditions cause fish to be more susceptible to infections. Inappropriate feeding can also contribute to health issues. Here are some ways to prevent swim bladder disease in aquarium fish:

  • Keep the tank clean and perform regular water changes.
  • Maintain a slightly higher water temperature to help digestion and possibly avoid constipation.
  • Feed your fish species-appropriate, high-quality foods.
  • Soak dried foods for a few minutes before feeding.
  • Thaw frozen foods thoroughly before placing them in the tank.
  • For fish who 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.

Is Swim Bladder Disease Contagious to Other Fish?

A swim bladder disease is not contagious from fish to fish. However, it's best if you move your sick fish to a separate tank where they can be treated and observed. The tank should be empty of gravel or plants so you can clearly see how the fish are doing. Use fresh water, and do not use water from the tank from which the fish came because the water could have caused the problem.

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.
The Spruce Pets uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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