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What Causes Swim Bladder Disorder and How to Treat It.

Swim bladder disorder is a condition that occurs in fish when their air bladder organ is compromised in some way. This usually results in diminished swimming ability or buoyancy issues. There are many causes of swim bladder disorder, most of which are treatable.

The air bladder, or swim bladder is the primary organ responsible for balance and buoyancy in fish. Through regulating the pressure of the organ, fish can maintain their position in a 3D space. When the bladder has issues regulating, fish can roll over on their side, swim upside down, or float at the top or bottom of the tank.

In this article, I’ll discuss some of the common conditions that result in swim bladder disorder, what causes them, and how they can be treated.


One of the most common causes of swim bladder disorder is constipation. The gastrointestinal (GI) tract lays against the swim bladder in a fish's abdomen. If the gut becomes plugged up, enlarged, or inflamed from constipation, it can easily push up against the swim bladder and cause dysregulation of pressure resulting in balance and buoyancy issues.


The most common causes of constipation in fish are:

  • Poor water quality

  • Improper diet

  • Low water temperature

  • Compressed gastrointestinal tract

Poor water quality is often the culprit for most fish ailments as this easily causes stress which leads to problems with maintaining homeostasis. Even though water quality is a catch all, it should always be the first thing you check when there is a problem. Start by testing ammonia, nitrite and nitrate. Then test for chlorine, phosphate, and heavy metals if the problem persists.

Poor water quality can specifically be responsible for constipation by causing problems with homeostasis. This basically means, due to stress, the fish is unable to properly digest its food. Imagine being sick and you develop digestion problems. The same thing happens with fish.

Improper diet can easily lead to constipation, especially with certain species. Goldfish, for example, have a compressed gastrointestinal tract due to ornamental breeding traits. This means their gut can easily become blocked from too much of, or the wrong type of food.

Fish flakes and other dried foods that soak up water can expand in the gut and block the GI tract, causing it to expand and press against the swim bladder. Even fish that are not bred with compressed GI tracts can ingest too much fiber or the wrong type of food and succumb to swim bladder disorder.

As ectotherms (cold-blooded), fish still produce some heat, but unlike endotherms (warm-blooded), they rely mostly on their environment to keep them warm. As the temperature of their environment decreases, their bodies can’t make up for the loss of warmth and they instead slow their bodily functions to compensate. One of the main functions that is compromised is digestion. With lower temperatures, fish digest food slower. This can lead to constipation within the gut.

As I mentioned with goldfish, some fish were bred for traits that make them appear a certain way. Sometimes, this results in their GI tract being compressed tightly. As the GI tract is right next to the swim bladder, it does not take much at all to put pressure on it. This is why goldfish, and other "balloon" modified species succumb to swim bladder disorder more often than any other species.


Some basic treatment options for constipation include:

  • Fasting

  • Feeding peas

  • Better water quality

  • Increase temperature

Fasting allows the GI tract to clear before adding more food which may block the tract even further. Fasting only works if the cause is undigested food blocking the GI tract, causing an enlarged portion of the intestines.

Most fish can easily survive fasting for 3-6 days. If the species in question is a herbivorous grazer, or similar species that requires constant food intake, you can feed a quarter or half portion of their normal diet once daily for a week.

Peas are a common treatment for constipation. They are moderately fibrous (less than most fish foods), highly nutritious, and easily digestible. To feed peas to your fish, partially boil them until soft and pinch the skin off between your fingers. Then cut the peas into smaller portions and feed once daily. Peas are especially good for goldfish and other herbivorous species.

Increasing the aquarium’s water quality is always going to help one way or another. At the very least it will reduce stress, resulting in a healthier fish, allowing them to recover quickly. Even if poor water quality is not the main cause, performing water changes to reduce toxic nutrient levels will help.

The one caveat with water changes to improve water quality is they can be done too often. A well performed water change doesn’t change the temperature, pH, general hardness, carbonate hardness, or any other parameters. It should only decrease the toxic nutrient levels. If you perform water changes too often or the other parameters change too drastically, this will stress your fish out and cause more harm than good. The key is to find a balance between the stress of a water change and the stress of high nutrient levels.

If your nitrates are above 40 ppm, or your ammonia is above 1 ppm, the stress of a water change is most likely worth it. However, if your ammonia is 0 ppm and nitrates are only 10ppm, you can probably wait on the water change, or perform a smaller one.

Finally, because fish are ectotherms (cold-blooded), they require external sources of heat to accommodate bodily functions. If the water temperature is too low, this can significantly slow down bodily functions, including digestion, and offset homeostasis.

Raising the temperature of the water will increase the rate of digestion. Raising the water temperature is a treatment if the temperature is too low. You shouldn’t permanently raise the water temperature more than one or two degrees above the normal temperature. For example, most tropical freshwater fish like a temperature between 74 and 78 degrees. If swim bladder disorder from constipation is occurring because the temperature is 72 degrees and slowing down digestion, then permanently raise the temperature to between 74 and 78. However, if the temperature is already at 76 degrees and your fish is experiencing swim bladder disorder, you can temporarily raise the temperature one or two degrees for a few days to aid in digestion. Make sure you lower it back to normal after the symptoms pass.


Swim bladder disorder can be caused by inflammation. Bacterial and parasitic infections are the number two causes of inflammation.


Inflammation is a body's natural response to an infection. Bacterial infections can result from wounds sustained in the tank, or compromised immune systems when a potent bacteria is present in the tank. Parasites, which can inhabit your tank naturally, can cause inflammation when they infect an unhealthy fish. Inflammation can occur anywhere, but affects the swim bladder when it occurs in the GI tract.


If the source of inflammation is determined to be a bacterial or parasitic infection, you can treat it with antibiotics or antiparasitic medication. However, if this is the case, swim bladder disorder is just a symptom. The underlying problem is the bacterial or parasitic infection which can cause much worse symptoms. You should determine what bacteria or parasite is infecting your tank and treat it. The swim bladder disorder will then alleviate itself along with the other symptoms. Check out my articles on diagnosing fish diseases, and ich to determine what may be infecting your tank.

Again, better water quality never hurts. Sometimes inflammation can be a tissue response to elevated levels of toxic nutrients. Elevated ammonia, for example, causes the gill filaments to become bright red and inflamed.

Enlarged Organs

Because the swim bladder is positioned in the abdomen, next to most of the internal viscera, enlarged abdominal organs can easily press against the swim bladder.


Here are a few reasons why neighboring organs to the swim bladder may become enlarged:

  • Cysts

  • Fatty deposits

  • Egg binding

Cysts on the kidneys or gallbladder can press up against the swim bladder. Also, the liver can develop fatty deposits which easily take up space in the abdominal cavity.

Egg binding occurs when a fish becomes gravid (laden with eggs) and the eggs, before they are secreted, become blocked in underdeveloped ovaries. As you can imagine, dozens and sometimes hundreds of eggs take up quite a bit of room and undoubtedly can press against the swim bladder. Egg binding is most common with outdoor koi and goldfish.


A better, more species-specific diet and higher water quality can help with fatty liver deposits and cysts. Adding a vitamin supplement to your fishes food or to the water directly will also help with these.

Egg binding can be treated by withholding food until spawning (egg release) is complete, raising the temperature a few degrees over several days to help develop the ovaries, and by massaging the abdomen to help release the bound eggs.


If you notice your fish are succumbing to swim bladder disease repeatedly, try only changing one aspect of their environment at a time. Wait to see if this variable or change has any effect. If not, change something else. Repeat this process until you find the factor responsible and eliminate it from your tank.



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