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Home > Betta fish > Bloated Betta Fish: Vet-Reviewed Causes, Signs, and Treatment

Bloated Betta Fish: Vet-Reviewed Causes, Signs, and Treatment

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Dr. Lauren Demos

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Betta or Siamese fighting fish are one of the most popular pet fish you can own. Although they are generally hardy and healthy fish, they can still develop certain health problems. One of these health problems is bloating, which can either be a sign of something minor or severe.

If you have started noticing that your betta fish’s belly is looking rounder than normal, your betta fish might be suffering from bloat. This article will guide you through the various signs to look out for and how you can treat your betta fish for this condition.


What Is Bloat in Betta Fish?

Bloat is an uncomfortable gastrointestinal condition that can affect many different species of fish, including bettas. It causes your betta’s stomach to protrude more than usual, making it appear swollen. Any betta fish can be affected by bloat, regardless of their variety, age, or genetics. It isn’t necessarily an illness itself, but rather a sign of another health problem or the result of improper care and diet. A bloated betta fish will show clear signs of discomfort.

What Are the Signs of a Bloated Betta Fish?

Signs that your betta fish might have bloat include:
  • Enlarged stomach
  • Lethargy
  • Decreased appetite
  • Abnormal swimming behavior
  • Clamped fins
  • Rapid breathing
  • Buoyancy issues

The first and most noticeable sign of a bloated betta is an abnormally large stomach. Their stomach is located along the upper half of their body, just below their gills and head. When their stomach is enlarged, it will protrude and affect them in several ways.

A bloated betta fish may have trouble swimming normally. They might swim lopsidedly or struggle to even swim at all if their bloating is affecting their buoyancy. This can lead them to become lethargic and even refuse food.

The 5 Main Causes of Betta Fish Bloat

1. Overfeeding

The most common reason for betta fish to experience a bout of bloat is from overfeeding. Betta fish don’t really know when enough is enough when it comes to food. They will try to eat all of the food you feed them, even if it means that they may suffer as a result. If you are overfeeding your betta, you might notice that their stomach looks bloated afterward. This is a major indication that you are feeding your betta fish too much food at once.

Betta Fish eating
Image By: Trillianvlmann, Shutterstock

2. Cancer/Tumors

Bettas can develop cancer or tumors which can make their stomach appear enlarged. This is usually true in cases where bettas have internal tumors in their stomachs. However, bettas can have an external tumor on their stomach that can be mistaken as bloat. Unfortunately, this is usually an untreatable health problem that doesn’t usually resolve itself. There may be little you can do to treat a betta fish with a tumor, and you might need to humanely euthanize them if it affects their quality of life.

3. Bacteria, Viruses, Parasites, or Protozoans

Certain bacterial or protozoan infections may cause your betta fish’s stomach to bloat. Internal parasites and viruses may also cause bloating, although wasting (hollow belly) is usually a more common sign. Some gram-negative or even gram-positive bacterial infections can affect your betta’s internal organs which may lead to swelling in their abdomens or coelomic distention (dropsy).

If a betta has a mycobacteria infection that is affecting their internal organs, they might develop dropsy. Dropsy isn’t a disease itself, but rather a sign of a disease. It is often fatal for betta fish, and they won’t live much longer once they start showing signs.

The only accurate way to determine what type of bacteria caused your betta’s dropsy and bloated appearance is to have their tissue tested in a laboratory.

dumbo betta fish in an aquarium flaring
Image Credit: panpilai paipa, Shutterstock

4. Incorrect Water Temperature

Water temperature plays a role in your betta’s metabolic functions, such as the way they process food. Bettas are tropical fish and their metabolism functions best in warmer waters between 72 to 82 degrees Fahrenheit (22°C to 27°C).

If they are kept in unheated aquariums, the water temperature can drop below their ideal range and may affect how they digest their food. If your betta is kept below their ideal temperature range in water temperatures below 69 degrees Fahrenheit, you might notice that your betta becomes bloated after a meal. This could be because your betta is having difficulty processing food properly in colder water. However, prolonged cold-water temperatures might even cause your betta to not eat at all.

5. Unsuitable Diet  

Bettas are carnivorous fish that can be fed an omnivorous diet in captivity. They are naturally suited to digesting animal-based foods like shrimp, insects, larvae, daphnia, and small crustaceans in the wild.

Bettas who are fed a completely plant-based diet or low-quality commercial foods may have issues with bloat. Certain commercial fish foods are loaded with fillers and artificial ingredients that your betta can have difficulty digesting, leading to bloating issues. The food might also contain more plant-based ingredients like algae rather than animal-based ones that betta fish need to keep healthy. Your betta fish should get most of their nutrition from a pellet or flake food formulated for bettas, along with live or frozen foods like bloodworms or brine shrimp.

woman feeding betta fish
Image Credit: Alexander Geiger, Shutterstock

pets 6

How Do I Care for a Betta Fish With Bloat?

Generally, prevention is better than cure for most fish health problems. Ensuring that your betta is living in the right conditions and fed a balanced diet is the best way to keep your betta healthy throughout their life.

Here's how you can care for your bloated betta fish:
  • House them in a spacious and filtered fish tank (ideally over 5 gallons in size).
  • Feed them a balanced carnivorous diet consisting of pellets and live or frozen foods.
  • Keep their aquarium heated to a temperature between 72 to 82 degrees Fahrenheit.
  • Only feed them fresh foods that are not expired or spoiled.
  • Offer your betta more live foods like daphnia, bloodworms, brine shrimp, and tubifex worms.
  • Feed them small portions of food once or twice a day that they can eat within a few minutes to prevent overfeeding.
  • Regularly test their water parameters and do weekly partial water changes.
  • Only keep them with compatible tank mates.

Usually, the wrong diet and water quality are to blame for your betta’s bloated stomach. Once they have been rectified, your betta’s stomach should return to normal within a couple of days. Making slight changes to their water quality, temperature, and diet is enough to combat minor cases of bloat in bettas.

However, if a bacterial infection, dropsy, or tumor is the cause of your betta’s swollen stomach, finding the right treatment is more challenging. If possible, we recommend looking for an aquatic veterinarian in your area who can take a look at your bloated betta fish. Bacterial infections or organ damage caused by certain diseases can be difficult to treat if you don’t know exactly what you are treating for.

Unless your betta fish is showing clear signs of a specific disease that you know a certain medication can fix, it’s better to not put your betta under more stress by filling their aquarium with medications.

pets 6 Frequently Asked Questions (FAQs)

Can you give a bloated or constipated betta fish peas?

There is a lot of misinformation on the exact cures for betta fish bloat. When humans are bloated or constipated, we usually need more water or fiber in our diets. However, this is not the case for fish who live in a completely different environment than us. Some people suggest that peas provide your betta with plenty of fiber to get things moving in their gastrointestinal tract to improve signs of bloating and constipation.

Peas are not a cure for betta fish bloat, and there is little evidence to prove that they help much. Bettas are naturally carnivores, so depriving them of their normal diet to replace it with peas might do more harm than good.

Bettas do not necessarily get bloated because they need more fiber or water in their diet. They live in water which is always moving throughout their bodies and getting processed by their kidneys. Furthermore, bettas receive enough fiber from animal-based foods like daphnia, so adding peas into their diet doesn’t change their fiber intake by much. Your betta is likely to get more beneficial fiber from gut-loaded daphnia than it is from peas.

Usually, if a bettas bloat is responding well to dietary changes, their previous diet might have been inadequate for them. Making changes to their diet to include foods they would naturally eat in the wild will keep their gastrointestinal system running smoothly.

Should you fast a bloated betta fish?

Thai Flag Betta Fish
Image Credit: Ekachai Sathittaweechai, Shutterstock

You should never fast your betta fish unless they are already refusing to eat. Food is important for bettas and although they can survive without food for a while, it isn’t ideal. Instead, you should feed them appropriately sized portions of food every day, and only enough that they can consume within 5 minutes. If your betta is not wanting to eat their food, you can skip their next meal to prevent the excess food from fouling the water and exacerbating any existing water quality issues.

Changing the type and frequency of food you offer your betta is usually enough to prevent them from becoming bloated if their diet is the issue.



There are several reasons why a betta fish can become bloated. Typically from an inadequate diet or living conditions that can easily be fixed. However, certain severe health problems like internal infections, organ damage, dropsy, and tumors can make your betta fish appear bloated. Unfortunately, they can be challenging to treat without the help of an aquatic veterinarian.

Most bloated bettas respond well to a combination of dietary and environmental changes, which may also help prevent your betta from getting bloated again.

Featured Image Credit: Wirestock Creators, Shutterstock

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