What is a betta fish tumor?

In this blog we will discuss betta fish tumors.This blog will help you learn about betta tumors and how to prevent and treat them.


In this blog

  • What is a betta fish tumor?
  • What are the reasons for tumors in bettas?
  • What are the symptoms of betta fish tumors?
  • Do abscess resemble bettas tumor?
  • Can we treat both external and internal tumors in bettas?
  • How to avoid tumors in betta fish?
  • How do you remove tumors from betta fish?
  • Do betta tumors affect their swimming pattern?
  • Why is there a tumor on my betta fish belly?
  • Summary 
  • Frequently asked questions
  • Reference

What is a betta fish tumor?

Most fish develop tumors due to their genetic predisposition. However, some fish can develop tumors due to viral infections.

For some poor-quality bettas, tumors are unavoidable, and there are few direct cures. The type and size of tumors determine whether they are harmful or not.

A benign tumor that can grow to a large size, rarely spreads to other parts of the body, and is generally of low risk.Large benign tumors can be too heavy for a betta fish to swim comfortably and should be removed by an aquatic veterinarian.

More troublesome forms of tumors contain cancer cells. It quickly spreads to major organs in the body and can cause problems.

Cases of mild tumors have completely recovered, while some severe cases have mild improvement but have not healed.

In most cases, these tumors cannot be successfully removed from any part of the body and the betta fish may need to be euthanized with the approval of an aquatic veterinarian.

What are the reasons for tumors in bettas?

  • Poor genetics- Tumors are usually caused by genetics. If one of the parents or ancestors in the betta fish family tree has a history of tumor,it is likely that the offspring will develop a tumor at some point in their lives.
  • Poorly bred betta fish- Betta fish thrown together for breeding can lead to under-breeding strains. This makes them more susceptible to various disorders and diseases. Inbreeding can be dangerous to their health and even shorten their life.
  • Allowing carcinogens in the betta aquarium.
  • Feeding bettas poor quality food- Poor quality foods may contain carcinogenic ingredients.Over time, these toxins can accumulate in the betta system and grow tumors.
  • Viral infections caused by poor water quality in bettas aquarium.

What are the symptoms of betta fish tumors?

  • Hard lumps or bumps sticking out of a betta body.
  • A betas tumor will look like a lump. Lumps can vary in size, sometimes they are small and sometimes they are large.
  • The betta bump or lumps continue to grow abnormally.
  • Due to the weight of the tumor, betta fish with tumors can be seen swimming sideways.
  • Betta fish with tumors lose their appetite. 
  • Betta fish with tumors can also appear jittery & lose all strength.
  • Betta body discolouration.
  • Inability to swim in the last stage.
  • Bettas become lethargic or listless.

Do abscess resemble bettas tumor?

Abscesses are caused by bacterial infections. Your betta may have been injured by something sharp in the aquarium, or the damage may have been caused by a bite from another fish.

An abscess is a white bump on bettas. It should not be confused with a tumor.The bumps on their body can be an ulcer or an abscess, which are very similar to tumors.Nothing to worry about abscess as it could heal on its own.

Can we treat both external and internal tumors in bettas?

Betta tumors can be external or internal. External tumors of betta fish are treated with either surgical resection/cryotherapy, which is a secondary topical treatment. Internal tumors may be difficult to understand and remove.

How to avoid tumors in betta fish?

If you are planning to get a new betta fish, buy it from a reputable breeder. Some fish companies raise their own inland fish because it is cheaper than importing them or raising them properly.

Inbred fish can suffer from a variety of problems and the increased likelihood of tumors is one of them.

Make sure to keep the aquarium water clean. Clean water will reduce your betta fish’s overall risk of disease.

Never feed your fish cheap and poor quality food. Make sure you feed your bettas high quality food and make sure they have a varied diet.

Keep carcinogens away from water and tanks. They will be a major cause of your betta tumor, so don’t put them near such things.

If your betta gets sick, be sure to treat it as soon as possible. If your fish has a weak immune system, it is more likely to contract more diseases.

How do you remove tumors from betta fish?

In bettas,external tumors can be removed.But this very risky operation should only be performed by a qualified, experienced tropical fish veterinarian. And there is no guarantee that the tumor will not recur in the future.

  • It is important to use treated water to remove tumors from bettas 
  • Always sterilize all equipment you use for tumor removal treatments.
  • Add clove oil to the treated water.
  • After adding the clove oil to the treated water, gently stir the water to completely disperse the clove oil in the water. 
  • Now transfer your betta to a shallow bowl, which contains your mix i.e treated water and clove oil. 
  • Oxygen supply and water flow are important throughout the process.
  • Make sure you are adjusting the oxygen levels with the help of a bulb according to the need.
  • Wash your hands thoroughly before transferring the fish to a shallow bowl.
  • Do not use the net for transferring as it can lose slime when transferred using the net.
  • In a few minutes they will fall asleep due to anesthesia.
  • Make sure they are completely asleep before removing them from the shallow bowl. 
  • Make sure they  are not jerking anymore.
  • Then transfer them to paper towels. 
  • Remove tumors with a sterile knife and forceps and by spraying conditioning water in between to keep them hydrated.
  • After removing the tumor, return it to clean water. This makes it easier to breathe after waking up.
  • Transfer them to a recovery tank equipped with a thermometer for 24-48 hours and observe them.
  • After they get up it is important to feed them properly.

Do betta tumors affect their swimming pattern?

If you observe lumps or bumps above or below the skin of a betta fish, it is likely a tumor. 

Tumors can be small and barely noticeable, or they can be huge. Tumors that cover large areas of the fish’s body can cause buoyancy problems and affect fish swimming.

Some tumors are internal and invisible to the naked eye. Internal tumors usually affect the ability of fish to eat and swim. It rapidly reduces the health of the fish.

Why is there a tumor on my betta fish belly?

Dropsy is swelling of the soft tissues of the body cavity, such as the abdomen, due to the accumulation of water and other fluids. This condition is caused by environmental stressors or infection. Dropsy should not be confused with tumors.


Tumors are a scary but common occurrence in betta fish. This occurs very often in betta fish and is usually unavoidable.Tumors in fish cannot heal and tend to re-grow even after surgery.

There are several causes of tumors in previously healthy bettas. These include poor diet, unsanitary water,viral infections and newly added fish species.

Tumors are found throughout the betta body. However, depending on the area, it may be something else, not a tumor. 

A betta tumor could be external or internal. External tumors can be removed surgically, but internal tumors require special attention and it is very important to consult a fish surgeon to treat the internal tumors.

Understanding betta tumors is important for all betta fish enthusiasts because it can occur at any stage of a betta fish’s life.

Just because you notice a betta tumor doesn’t mean it’s over. Many have found that their bettas lived a full life despite having tumors.

Frequently asked questions

Do bettas get tumors on their head?

One place that betta keepers tend to notice a tumor is on their betta’s head. A lump on your bettas head could also be a sign of a bacterial infection.

Do betta get a tumor on the sides of their bodies? 

You may notice a bump on the side of your betta. Again, this may or may not be a tumor.

Is tumor removal in bettas permanent?

There is no guarantee that tumors in the fish will be removed, nor that they will be completely cured or not recur after surgery. But excision is important because the tumor doesn’t allow the fish to swim normally.

What do bettas with tumors look like?

Affected betta fish may have swelling, protruding scales, or signs of abnormal swimming patterns.Owners usually notice changes in the appearance of fish after the tumor has grown sufficiently.