Swim Bladder Disease: Causes, Symptoms, and Treatment

swim bladder disease

Swim bladder disease is also known as flip-over. This is the disorder that affects the buoyancy of a fish. In case you don’t know what buoyancy is, it is an upward force that pushes an object to go up if it is submerged in water. The buoyancy force decides whether the object sinks or floats. You might have wondered anytime in your life how a fish floats at the surface and how it swims easily all-around in water. And what if your fish is not doing it right! It can have a problem that is affecting its buoyancy.

Another question that arises is how does a fish maintain its buoyancy. Well! The special thank goes to an organ called a swim bladder. And if swim bladder s not working properly, it causes swim bladder disease. Here we are going to discuss everything about swim bladder disease from what it is to the treatment and prevention possible. Stay tuned!

To know more about different Saltwater and Freshwater Aquarium Fish Diseases, click this article “Aquarium Fish Diseases: Causes, Symptoms, and Treatments“.

What is a swim bladder?

The swim bladder is a specialized organ enclosed in a tough membrane. It is present at the end of all vital organs. It is similar to the buoyancy compensation device that divers use. The swim bladder contains gases and oxygen, which maintains natural buoyancy. This allows fish to swim at its desired depth.

Now let’s see how swim bladder works. The fish take in oxygen by gulping air at the surface. The oxygen is then transported to the bladder via the pneumatic tract. Fish displace water, to float or to be buoyant. The amount of water it displaces should be equal to or greater than its body mass.

Swim bladder can contract or expand according to the gas inside it. When it expands, it displaces more water and the fish floats. In contrast, when swim bladder deflates, it displaces less water and sinks. The reason is buoyancy increases when swim bladder expands and buoyancy decreases when it deflates.

Swim bladder functions in two ways. Some fish, called physostomous, inflate or deflate the bladder by gulping and expelling air through a duct. Whereas, other fishes, called physoclistous, inflate and deflate swim bladder by the exchange of gases through a network of blood vessels. However, some fish even don’t have this classification and some have both systems. Some fish also produce and detect sound using their swim bladder. Overall, this organ is very important for the health of a fish. 

There are two conditions related to buoyancy disorders; positive buoyancy disorder and negative buoyancy disorder. A fish with a positive buoyancy disorder will float on the surface of the water. Due to this, it’s a portion of its skin will be exposed to air. This exposure of skin to air disrupts the protective mucous barrier leading to ulceration and infection of exposed skin scales.

On the other hand, if a fish has a negative buoyancy disorder, it will stay on the bottom of the tank. Staying too low, the fish will rub with the substrate that will disrupt the protective mucous barrier and ulceration and skin infections afterward.

Buoyancy disorders have rapid onset and prognosis for long-term survival is also low. Therefore, it is better to prevent it and to know about the causes and treatment and how you can prevent it. 

Symptoms of swim bladder disease

Despite swimming abnormally, some signs can warn you that the health of your fish is declining. Symptoms of swim bladder disease are:

  • Floating at the top
  • Sinking to the bottom
  • Unable to maintain a normal position
  • Floating side-ways or upside down
  • Curved back
  • Distended belly
  • Swims with a tail high
  • May have normal or no appetite

Causes of swim bladder disease

Understanding the causes of swim bladder disease is important to prevent and treat it. Causes are as follows:

  • Tiny organs of fish such as the stomach, liver and intestines can become enlarged. These enlarged organs press against the swim bladder and cause it to malfunction. Egg binding in female fish, fatty deposits in liver or cysts in kidneys cause enlargement, thus affecting the swim bladder.
  • Gulping air while eating, overeating and rapidly eating causes the stomach to distend. Overeating causes fatty deposits in the liver.
  • Eating low-quality or air-filled food causes constipation
  • Eating dry flake or freeze-dried food because it expands when it becomes wet. Thus causing the stomach and intestines to enlarge.
  • Poor water quality causes sudden and chronic stress in fish. This disrupts regular homeostasis, resulting in positive or negative buoyancy disorders. 
  • Bacterial or parasitic infection causes complications in the swim bladder.
  • If swim bladder disease is a birth defect, symptoms would be present at an early age. 
  • Low water temperature slows down the digestive process. This leads to the enlargement of the gastrointestinal tract.

Treatment for swim bladder disease

Though the swim bladder disease is not contagious, in a sense, that other fish will not catch it if one fish has swim bladder disease. However, because they are living in the same environment, other fish can develop similar problems. Some treatment options of the swim bladder are:


Eating problems such as overeating or not being able to digest food properly, commonly cause swim bladder disorder. What you can do is to let your fish fast for three days. This will allow the fish to digest the already eaten food. This will also give stomach, intestines and other organs some time to get back to their size. 

Give cooked peas to fish

As peas are dense food and are high in fiber, it treats constipation problems. You can use frozen peas for this purpose that would be good. You can microwave or boil them for a few seconds, but make sure that they are not mushy. If they are mushy, peas will fall apart before fish can eat them. Skin peas before giving them to fish. Make sure that you don’t give a pea or two per day until the problem resolves. After that, you can use species-appropriate food. Avoid food that floats, such as flakes and pellets. The reason is that fish gulp too much air while eating such kinds of food.

Raise the water temperature

As it is mentioned before, lower water temperature reduces the efficiency of the digestive system, and it causes constipation. To cure this, increase the water temperature to 70-80 degrees Fahrenheit. This will help the fish to digest the food properly.

Feed fish by hand

If your fish with swim bladder disease has trouble going down to eat peas, try to feed it by hand. You can also use a skewer to bring the pea close to the fish. Lowering the water level will also help.


If the sim bladder disease of a fish is due to infection, your vet may prescribe you antibiotics, a broad-spectrum of antibiotics are available that can cure the swim bladder disease.

Epsom salt to cure swim bladder disease

Giving Epsom salt to your fish may seem shocking, but it helps your fish to get rid of a swim bladder disorder. However, you should be careful enough while using Epsom salt. In case you don’t know about Epsom salt, it is magnesium sulfate. It is also effective for humans as a laxative and to reduce swelling.

What Epsom salt does to your fish is that it helps your fish to get rid of backed up waste. It can also reduce swelling that could be the result of a disease or an infection.

To prepare a salt dip, you need:

  • A clean 1-gallon container that is used only for fish
  • A small container
  • Water conditioner
  • A measuring spoon
  • Thermometer
  • Net
  • 1 tablespoon Epsom salt


  • Fill the gallon container with treated water. Make sure the temperature of the water is the same as that of water in the tank to avoid shock.
  • Add salt and stir it until it is dissolved completely. 
  • To make a reviving station in the second container, fill 1/4th of the container with salted water and the rest with tank water.  
  • Carefully take your fish from the aquarium and put it in the water. Make sure that the fish doesn’t pass out. If it does, remove and put it into the reviving station. When it revives, bring it back to its home and try salt dip another.
  • If fish doesn’t get stressed, keep it for 10-15 minutes in the dip. Keep it for 10 minutes if the condition of the fish is less severe and 15 minutes for the more severe condition. Make sure that you don’t exceed the time.
  • When it’s done, put the fish into the reviving station to let it adjust back to normal water parameters. Finally, put the fish back into the aquarium.

During and after the treatment, make sure that you monitor the symptoms carefully. Depending on the conditions, the swim bladder disease can be temporary or permanent. After the treatment, if symptoms don’t go away and your fish never regains its ability to eat or swim properly, then the most humane solution you are left with is euthanasia.

Swim bladder disease in goldfish

Goldfish are more prone to developing swim bladder disease. Goldfish have an open connection between swim bladder and esophagus. You might have remembered the term we used for such fish, the physostomous. This open connection makes buoyancy disorders more complicated. Due to their round body shape or much-curved spine, as in the case of fancy goldfish, swim bladder disease in goldfish is often due to deformed swim bladder.

Though swim bladder disease is very common in goldfish, the causes, as well as treatment, are the same. You should be observant enough to monitor the signs.

Prevention of swim bladder disease

Prevention is almost similar to treatment options. You can prevent swim bladder disease by taking the following precautionary measure:

  • Keep water conditions optimal by regularly changing water and keeping the tank clean. Also check pH, nitrite and ammonia level using a water test kit.
  • Keep water temperature appropriate
  • Feed good quality food and try to soak it before giving it to fish. When you soak food, the food sinks into the water. This allows fish to eat food without gulping much air. 
  • Feed smaller portions to prevent fish from overeating. This will reduce the risk of stomach and intestine enlargement and also the risk of constipation.
  • Reduce water flow in tanks with the strong current
  • Add some aquarium salt to the tank. Aquarium salt boosts the immune system and helps fight disease.
  • If the fish floats on the surface and its skin is exposed to air, you can apply a bit of stress coat. This will prevent the development of sores.


Whenever you keep a pet, it is important to take care of its health. We have provided you enough information to inform you about the symptoms, causes, and treatment of swim bladder disease. You can take precautionary measures to prevent it; however, if your fish does develop swim bladder disease, make sure to contact your vet immediately. Your vet will diagnose the condition accurately and will prescribe appropriate treatment for your fish.

To know more about different Saltwater and Freshwater Aquarium Fish Diseases, click this article “Aquarium Fish Diseases: Causes, Symptoms, and Treatments“.