bloated betta

Bloated Betta: Causes and Treatments

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One of the most common health problems in betta fish is bloat. But what causes a bloated betta, and will the condition kill your fish?

In this article, we talk you through the most likely causes of bloat in betta fish. We also take a look at what you can do to treat the problem and prevent it from happening again.

What is bloat in betta fish?

A bloated betta will appear to have a swollen, protruding belly. Bloat can affect one or both sides of the fish, sometimes causing him to appear lopsided.

A fish with bloat may have trouble swimming and may become trapped at the surface of the water or on the bottom of the tank. That’s extremely dangerous for betta fish because they need to surface frequently to breathe.

What causes bloat in betta fish?

There are a number of conditions that cause bloat in betta fish.


The primary cause of bloat in betta fish is constipation.

Constipation is extremely easy to treat and prevent, so although the condition may look alarming, you need not worry too much about your fishy friend, as it’s highly likely that you’ll be able to cure him pretty easily.


In addition to a bloated belly, the following symptoms are a reliable sign of constipation:

Poor Appetite: Bettas are notoriously greedy fish, so you’ll soon notice if your betta isn’t eating as voraciously as he usually does. A constipated fish will quickly stop eating, and that’s typically the first sign that your betta is constipated.

Less Waste: If your betta is constipated, he won’t be able to pass feces. However, bettas don’t produce a lot of waste, so it can be difficult to tell if your fish is pooping normally!


If you know what makes your fish constipated in the first place, you can take steps to prevent it. So, what causes constipation?

  • Poor Diet: The main cause of constipation in fish is poor diet. If you feed your fish too much poor-quality food, it can result in constipation, leading to bloating. Always give your fish the very best quality betta pellets, and include frozen, freeze-dried, and live food in his diet too. Avoid feeding betta fish flake food, as that can very easily cause constipation.
    • Feed your betta fish only as much as he will eat within a couple of minutes. Also, leave one day per week when you don’t feed your betta at all. That “fasting” day will allow excess food to pass through the fish’s digestive tract, rather than becoming blocked up.
  • Lack of Exercise: Fish need exercise! Yes, that’s right; your betta fish needs to keep moving around to help push food through his digestive system. If you keep your betta in a tank that’s too small, he will get bored and frustrated, as well as being at risk of becoming constipated.

Remember, wild male betta fish have a territory of around three square feet, so a tiny bowl or betta vase is simply not a humane environment for your fish!

Your betta should be kept in a tank that’s at least ten gallons in capacity, preferably bigger. You can read all about how to correctly set up a betta habitat in the article at this link.


The treatment of constipation in betta fish is extremely simple. Usually, fasting your betta for two to three days is sufficient to get their bowels moving properly again. 

After the fasting period, start feeding your betta live food, including daphnia, brine shrimp, and mosquito larvae. These foods will introduce more fiber into the fish’s digestive system, which will, in turn, relieve your fishy friend’s constipation.

Swim bladder disease

Swim bladder disease is another common cause of bloat in betta fish. However, swim bladder problems can also be caused by constipation and vice versa.

Swim bladder disease is actually not a disease in the truest sense of the word; it’s simply the common name that’s given to the condition. Swim bladder disease can affect most species of fish, including bettas.


A fish with swim bladder disease will have a bloated belly and will struggle to swim properly. You’ll notice that your fish is having problems with buoyancy, sinking to the bottom of the tank, or being stuck on the surface. Sometimes, fish with swim bladder disease become trapped on one side and can barely swim at all.

Fish with swim bladder disease typically have a reduced appetite, and, in extreme cases, your betta could develop a curved back.


There are several causes of swim bladder disease

  • Constipation: Like bloating, swim bladder disease is often caused by constipation.
  • Injury: Swim bladder problems can also be caused by an injury. Injuries occur as a result of nips from aggressive tankmates or by your betta fish, damaging himself on something sharp or rough in his tank.
    • Your betta might even jump out of his tank and injure himself on landing. So, always put a lid on your betta tank or at least cover it, leaving an inch or so between the water surface and the cover so that your betta can breathe and feed easily.
  • Infection:  In rare cases, swim bladder disease in betta fish can be caused by bacterial infection or attack by parasites. In these cases, you may notice that your betta’s feces are very pale in color and are stringy, rather than firm and dark brown.
  • Shock: Shock can also cause swim bladder problems. Shock in fish can be caused by temperature changes, fluctuations in the correct water pH, and frequent changes in the lighting in the tank. In cases of shock, fixing the underlying cause usually cures the swim bladder problem too.
  • Treatment

There are several ways of treating swim bladder disease, depending on the cause.

Try fasting your fish for a few days, and then offering him live or frozen food. If that treatment is unsuccessful, try using a proprietary swim bladder treatment that you can buy over-the-counter in most good fish stores. 


Dropsy is another cause of bloat in betta fish. Unfortunately, dropsy is very difficult to treat, and there is a good chance that your fish will die or that you will need to euthanize him humanely. 


In addition to a bloated appearance, fish with dropsy develop “pinecone” scales. That’s where the scales stand up, giving the fish the appearance of a pinecone. The effect is caused by internal organ damage. The damaged organs swell, causing the fish’s body to bloat, and pushing the scales outward. 

As the internal swelling increases, the fish’s spine begins to curve outward sideways.


Dropsy has a variety of causes:

  • Stress: Stress in betta fish that often leads to dropsy is often caused by poor water quality, incorrect diet, and other illnesses. Continued exposure to stress weakens the fish and damages his immune system until he can no longer fight off illness.
  • Internal Injury: Internal damage can cause the betta’s internal organs to swell as part of the healing process, giving your fish a bloated appearance. Internal injury can happen during your betta’s move from the fish store to his new home.
    • Bettas can also sustain internal injuries by bumping into objects inside the tank or fighting.
  • Infection: Bacterial diseases can also cause dropsy.


Unfortunately, dropsy is incredibly difficult to treat successfully.

However, you could try to aid your betta’s recovery by carrying out frequent water changes and administering an antibacterial or antibiotic. It may also be worth trying dipping your betta in methylene blue.

Malawi bloat

Malawi bloat is a rare condition that commonly affects cichlids, although it is sometimes seen in betta fish.  


Malawi bloat causes the fish to swell. Also, your betta may stop eating. As the condition progresses, the fish will spend a lot of his time at the surface of the water, gulping air.


Malawi bloat is caused by parasites or bacteria in the tank water.

The best way to prevent the condition is by keeping your tank water clean. If you buy live plants or live food, always make sure that the supplier has a good reputation, and never try to source live food from the natural environment, as you could be unwittingly introducing disease into your tank.


Sometimes, a bloated belly in a betta fish can be caused by an internal tumor. 

It’s not possible to prevent tumors from affecting your betta. Just like people, some fish develop cancer, and there’s nothing you can do about that. That said, tumors aren’t very common in bettas, and it’s more likely that your fish’s condition is caused by something else.


If you have a sorority of female betta fish in a tank with a male betta and it’s a female fish that is bloated, it’s possible that condition could be caused by eggs inside the fish.

Other signs to look out for include the appearance of white horizontal stripes running across the fish’s body and the appearance of an obvious white spot on the fish’s abdomen. The white spot is the opening of the ovipositor, a tube through which the eggs are dropped.

Bloated betta? Take action right away!

The best way to give your bloated betta the best chance of recovery is to act quickly; don’t wait for a few days to see if the condition simply disappears!

The first thing to do is to try to diagnose what’s causing your betta to be bloated. 

If the problem is simply caused by constipation, then your fish can stay in his main tank. 

However, if you’re not convinced that constipation is causing your betta’s bloat and he lives with a community of other fish, then you should move him to a quarantine tank. 

Moving your fish will stress him to some degree, but a temporary relocation will prevent his tankmates from becoming sick. Also, treating your betta will be much easier if he’s living in isolation, and he will find it easier to rest and recover without being hassled by his tankmates.

Once you have moved your betta fish to the quarantine tank, start whatever treatment is appropriate. Keep your betta in quarantine until he has made a full recovery. The stress of moving him back to your display tank could trigger a relapse if your betta hasn’t completely recovered from whatever caused him to bloat.

While your betta is undergoing treatment, be sure to observe him carefully for changes in his condition.

Preventing bloat in betta fish

Prevention is definitely better than cure when it comes to bloat. Disease prevention is actually pretty straightforward.


Always provide your fish with a clean tank. Performing 25% water changes each week will help to remove ammonia and fish waste from the tank. Also, water changes can help to remove harmful parasites and bacteria from the tank.

The lower the levels of ammonia and organic waste products that your tank contains, the lower the levels of nitrites and nitrates will be, which is great news for your fish. You should also have a proper filtration system installed in the tank to process and remove nitrites and nitrates from the water, keeping the environment healthy for your fish.


The water temperature in your betta’s tank should be a constant 780 Fahrenheit. If the temperature falls too low, your betta could suffer from temperature shock, which will expose him to diseases and make it harder for him to digest his food, potentially causing constipation and bloat.

Proper Diet

Make sure that everything you feed to your fish is of the highest quality. Keep your betta’s diet well-balanced by feeding him betta pellets, and remember to include some live food, freeze-dried protein, and frozen food, such as bloodworms, daphnia, mosquito larvae, etc.

Tankmates and Decor

Ensure that the tank environment is safe for your betta fish. Avoid introducing aggressive tankmates, and use only smooth-sided decorations and live plants, rather than sharp plastic ones, which could injure your betta.

Tank Size

Keep your betta in a tank that’s at least ten gallons in capacity. Never overcrowd the tank. Too many fish in the habitat places an increased burden on the filtration system and will also stress your betta.

In summary

Bloat is a common condition that affects betta fish. Fortunately, most of the causes of bloat are easily treatable. 

You can prevent bloat from affecting your betta fish by ensuring that his tank environment is suitable and safe for him. Feed your betta a high-quality diet of betta fish pellets, and be sure to include plenty of live, freeze-dried, and frozen meat protein too.

If your betta develops bloat and you think it may be caused by a disease, rather than by constipation, move your fish into a quarantine tank where he can be treated in isolation. That will protect the community in your display tank from diseases. Wait until your betta has completely recovered before you return him to the main tank, and be sure to remain vigilant for further problems immediately following his reintroduction to the community environment.

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