Swim Bladder Disease in Fish: Causes, Symptoms & Treatment

Swim bladder disease is a serious disease that can affect your fish. It causes the fish to swim in an abnormal manner, and they may be unable to swim upright.

The disease is caused by bacterial infection, and poor water conditions, but it can be treated with antibiotics and proper care.

The swim bladder is a sac-like organ that helps the fish control its buoyancy in the water.

When the swim bladder is diseased, the fish can’t maintain its balance and may float or sink to the bottom of the tank.

Swim Bladder Disease of Fish

What is Swim Bladder in Fish?

Swim bladder is the name for the gas-filled organ in fish that helps them stay afloat. Most fishes possess a sac-like construct positioned between the gut and the kidneys.

The structure is called by other names, such as swim-bladder, gas-bladder, or air-bladder.

The swim bladder is located in the abdomen and is filled with either air or gas. In some fish, the swim bladder can be used to adjust their buoyancy.

Fish use the swim bladder to adjust their position in the water for feeding, breeding, and hiding from predators.

The swim bladders of marine fish are somewhat smaller than those of freshwater fish as salt water is more denser than freshwater.

The swim bladder of a marine fish comprises about 5 percent of its volume; of a freshwater fish, this is about 7 percent.

The swim-bladder can be divided into two types depending on the region between the swim-bladder and the oesophagus: Physostomus and Physoclistous.

A variety of fish with an air bladder hang out along with its gut, and a control mechanism is attached to the bladder so that they can regulate gas intake. This is referred to as a Physostomous state.

In some other species, the intestinal pathway is shut off and won’t allow gas to flow between the two areas. This is known as the Physoclistic condition.

It is located on the upper back, opposite the head, at the location where the two chambers would normally be found.

The exact shape and dimensions of the actual organ may vary between different species.

Functions of Fish Swim Bladder

The swim bladder has two main functions: to keep the fish afloat and to help with movement.

1. Hydrostatic organ

2. Adjustable float

3. Maintaining Gravity

4. Respiration

5. Sound Creation

The swim bladder is a gas-filled organ in fish that helps them control their buoyancy.

The bladder can be inflated or deflated to adjust the fish’s position in the water.

-The gas in the swim bladder can also help the fish move through the water. When the fish needs to move quickly, it can release gas from the swim bladder to make itself more streamlined.

How Does Swim Bladder Work

The buoyancy-regulating organ is a rich and intricate organ and may be controlled by multiple populations of autonomic neurons.

Fish control their volume through thin membranes comprised of many capillaries. Gas exchange happens via the capillaries and the membrane.

The capillaries of both both arteries and veins are arranged so that they serve as an aid to alter the pressure in the swim bladder.

How does swim bladder work
Source: wikimedia.org

What is Swim Bladder Disease?

Swim bladder disease is a condition that can occur when the swim bladder becomes inflamed or infected.

This can cause the fish to become unable to maintain their balance and they may float or sink.

Swim bladder disease can be caused by a variety of factors, including parasites, bacteria, and toxins.

Treatment for swim bladder disease may include antibiotics, anti-parasitic medications, or surgery.

Causes of Swim Bladder Disorder

Swim bladder disease is a common problem in fish that can be caused by a variety of factors.

Bacterial infection, parasites, and environmental stressors are all possible causes of swim bladder disease.

Bacterial infection

The most common cause of swim bladder disease is bacterial infection. Bacteria can enter the fish’s body through wounds or by passing through the gills.

Aeromonas hydrophila and Shewanella xiamenensis were the probable causative agent for bacterial infection in the swim bladder.

Once inside, they can travel to the swim bladder and cause inflammation and infection.

Physical Injury

When a fish is injured, the swim bladder can become damaged. This can happen if the fish is hit by a blunt object, or if it suffers from a puncture wound.

If the swim bladder becomes damaged, the fish will have trouble maintaining its balance and will often float to the surface of the water.


Another most common causes is transportation. This can lead to a number of serious health problems for the fish, including death.

When fish are transported long distances, the sudden change in water temperature and pressure can cause the swim bladder to expand and rupture.

Water Quality

When the water quality is poor, it can cause the swim bladder to become inflamed and enlarge.

The main causes of swim bladder disease are high levels of ammonia and nitrates in the water.

These pollutants can cause the fish to become weak and lethargic, making it difficult for them to swim properly.

The swim bladder will then start to enlarge as a way of compensating for this.

Swim Bladder Disease Symptoms

The most common swim bladder disease symptom is a fish that floats at the surface of the water.

– Abnormal swimming patterns, resting on the bottom of the tank, and changes in behavior.

-Complete loss of physical balance.

-Dilated blood vessels and hemorrhages on the swim bladder.

-Swim bladder deformation, excess fluid accumulation, collapse, over inflation, and herniation.

-Abdominal swelling due to accumulation of clear fluid within the swim bladder and abnormal swimming behavior.

-The epithelium of the swim bladder becomes multilayered and edematous.

As the disease progresses, lymphocytes infiltrate the bladder wall and surrounding areas and secondary infections occur.

Swim Bladder Disease Treatment

There are several treatments available for swim bladder disease, and early diagnosis is key to preventing any serious complications. Here is How to cure swim bladder disease,

Antibiotic Treatment

Treatment typically involves antibiotics or anti-parasitic medications, depending on the underlying cause of the condition.

Sulfamethoxazole and Ampicillin are effective to treat swim bladder infections. Vitamin C is mixed with medicated feed may be effective to improve immunity in the fish body.

Dip Treatment

3 ppm potassium permanganate is used for 3-4 minutes.

Salt Bath

Add one tablespoon of aquarium salt per gallon of water.

Regular Water Change

Partial water exchange may help to reduce the organic load from the tank water. The water quality parameter may also become balanced.

This will help to keep the water parameters stable and will help to prevent any unwanted bacteria or algae from growing.

Melafix for Swim Bladder Disease

Melafix, an herbal remedy made from the extract of the neem tree. Melafix is said to help improve the function of the swim bladder and promote healing.

It is non-toxic and safe for use in fish tanks. It helps to restore the balance of bacteria in the tank and can help to clear up the infection.

It also helps to promote healing of any injuries that may have caused swim bladder disease.

It can be used alone or in combination with other treatments.

Prevention of Fish Swim Bladder Disorder

There are several steps you can take to help prevent your fish from developing swim bladder disease.

Balanced Healthy Diet

One of the most important things you can do is to ensure that your fish are eating a healthy, balanced and proper sized diet.

Fish need plenty of protein and fiber to maintain their health, so make sure they are getting fed a balanced diet.

Reduced Stocking Density

Avoid high stocking density and make sure your fish have plenty of space to swim.

If they are cramped together in a small tank, they will be more likely to develop the disease.

Good Water Quality

Another way to prevent swim bladder disease is by maintaining good water quality in your tank.

You should also test the water quality parameter (pH, Do, ammonia, Nitrite, or Nitrate level) and make sure it is within the appropriate range for your type of fish.

If the levels of ammonia or nitrates are high, you will need to take steps to reduce them.

Proper Handling During Transportation

There are several things you can do to help prevent swim bladder disease in your fish during transportation.

Make sure that you use a properly aerated container filled with cold water.

You should also add a stress reliever such as salt or aquarium supplements to the water.

Ensure Healthy Environment

Keep the water temperature consistent by using a heater or chiller as needed.

Make sure to keep the tank clean and free of debris. Replace contaminated and dirty water with fresh and clean water.

Proper Monitoring and Maintenance

Fish with swim bladder disease should be monitored closely and treated as necessary to prevent further health problems.

One of the best ways to prevent swim bladder disease is by keeping the water quality stable. This can be done by performing regular water changes.

Swim Bladder Disease in Pond Fish

Frequently Asked Questions (FAQs)

Do all fishes have swim bladder?

Not all fish have a swim bladder; some deep-sea bottom inhabitants, some teleosts, and all the cartilaginous fish, such as the sharks and rays, do not have any bladder.

Sharks and rays use their pectoral fins to generate lift, similar to how birds use their wings.

How long can a fish live with swim bladder disease?

If left untreated, swim bladder disease can be fatal. In most cases, however, a fish with swim bladder disease can be expected to make a full recovery within several weeks.

Is swim bladder disease fatal?

Swim bladder disease is a common ailment in fish. It is not fatal in most cases but can cause problems for the fish if left untreated.

Is swim bladder disease contagious?

Swim bladder disease is not contagious, but difficult to cure. However, there are treatments that can help improve the condition of the fish.

Is swim bladder disease painful?

Swim bladder disease is usually painful, and disturbing situation for affected fish. In severe cases, the fish may not be able to swim at all and will die.


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