Betta Fish Tumor: Symptoms, Causes & Treatment

Have you been noticing tiny or large bumps on your betta’s body? Then with a heavy heart let me tell you that your fish might be suffering from a tumor. Betta fish can catch disease with time or carelessness. A tumor in your betta can signify the end of your betta’s life but keep your wits in control for now.

A Betta fish tumor is a bump or a lump under the fish skin. External tumor are easily noticeable. However internal tumors are silent and when you find them it’s already too late to treat them.

A tumor in your betta is a sign of underlying health issues that need to be addressed quickly. A very common cause of tumors in betta is because of cancerous cells. Although this disease is not very common in the betta community, yet still it occurs. Therefore, you have to take extra care of your fish, not show any irresponsibility from their side, and try to maintain a healthy lifestyle for your fish.

Betta Fish Tumor

You may ask, what causes tumors? How can you treat it? How do you prevent it from happening? Thus, here in this article, we have laid down all the possible reasons, symptoms, and methods of cure that you could use to help your betta get well soon. So, to give a clear overall view of this disease let’s begin from the very start.

How to recognize tumors in your betta?

Tumors are usually noticeable when there are lumps or bumps underneath your betta’s skin. They can either be tiny which makes them barely noticeable or they could be huge, big enough to be seen with the naked eye. Tumors that are big and cover large areas of a bettas body cause problems for them, either in their swimming or buoyancy or in both.

On the other hand, some tumors are internal. They spread internally inside the betta affecting its ability to eat and swim. This tumor weakens the fish to such an extent that treatment is not possible and your fish might die. this tumor cannot be seen with the naked eye therefore we don’t notice anything until it has done its work from the inside.

How does a betta get a tumor? Causes of tumor in betta

If your fish has caught a tumor, then don’t blame it on yourself. Sometimes there are fish that are already pre-disposed to tumors.  So, regardless of everything that you might have done to stop it from spreading it just had to happen. But sometimes they are caused in a previously healthy betta because of poor food quality, and viral infections that your fish might catch due to poor water and tank conditions. Introducing a new fish to the tank, and bad water quality. All these reasons mentioned here may seem like small acts right now but trust me it is these small situations where your fish can catch any disease.

How likely is it that your betta might grow a tumor?

If you see a lump or bump on your betta then don’t be so quick to judge as it could be something else. Tumors in betta are very rare, so there is no need to feel tense if you see a bump on your fish. This is because if you notice something that appears to be a tumor that in return rather that could be symptoms of some other diseases such as a swim bladder infection, an injury on your fish, constipation, fluid retention, or even bacterial infections can develop an abscess or ulcers in your betta, and unhealthy water conditions in the aquarium. So don’t panic too much, examine your fish first and then diagnose it.

Symptoms of Betta Tumor

One of the most common and obvious symptoms of a tumor in your betta is the lump. The size of the bump can vary, as sometimes they are huge, and sometimes they’re of normal size.

There are cases when there is no lump on your fish, this is because the tumor is emerging internally and not externally. Internal tumors or brain tumors are hard to detect in the early stages as they cannot be seen with the naked eye. Other tumors in betta can show symptoms such as

  • Not eating properly
  • Lethargy
  • Difficulty with balance and swimming

It is far less likely that your fish has a tumor because such symptoms or problems can be caused by another kind of illness. You can read through it to get a clear understanding in detail.

What if your betta has a white tumor?

Many people often notice a white lump on their betta’s head and confuse it with a tumor. Although it is a tumor, this tumor is not cancerous. Rather this white spot could be a sign of:

  • Abscesses
  • Ulcers
  • Other conditions

1. Abscesses

Abscesses is a bacterial infection. This may have formed when your fish comes into contact with an injury either by getting into a fight with another fish or hitting itself with an object or the tank. when such injuries happen, they are more likely to clear up on their own, but if the water conditions are not so good then the bacteria can enter the wound and lay an infection.

When the bacteria enter the body, it destroys the tissues upon coming in, which forms pus in that area. This keeps on gathering underneath the fish’s skin making a lump or it could be abscesses.

If this is not treated then the infection/ abscesses continue to grow to the point where the skin of the fish can’t take it anymore and then bursts. When this happens, the fish is left with a large open sore on its body, making the fish more vulnerable to getting further diseases from bacterial or fungal attacks.


You have to take extra care of your fish during this situation, as when you see that the lump is about to pop then it’s much better that you quarantine the fish in a separate tank, but do it carefully. This is done to protect other fish from getting infected by this.

Make sure to do frequent water changes of the hospital tank, especially once the bump has exploded to remove all germs and bacteria. In this state your fish becomes very stressed and might look for a place to hide, therefore, you should add soft objects to the tank where the fish can hide and loos stress.

2. Ulcers

Ulcers are bacterial infections. Bacteria already exist in the tank despite cleanliness, but these bacteria cannot harm the fish because of good health. But if the fish is under stress due to inadequate water conditions, then its immune system weakens and makes it more prone to getting diseases. Thus, at that time the bacteria attacks and causes ulcers in your betta.

This infection is easily identifiable because it causes redness around the lump and it is sore looking.

When fish has ulcers, they often seem lethargic to such a point that they stop consuming food.

When you see and feel that your fish might have ulcers then you should quickly place it in the quarantine tank and treat it. Even if the ulcer clears don’t place your fish back in the tank as your fish might catch a fungal infection. Therefore, keep it in the hospital tank for two to three weeks following proper treatment. Make sure to do frequent water changes, add aquarium salt to the tank, and make sure to use the correct measures (one teaspoon for every gallon of water). This will help in the healing process and get rid of germs.

Related Post: White Spots On Goldfish

Where can tumors be located?

Tumors can occur anywhere on your betta’s body. However, since we already mentioned that not all bumps are tumors, rather they can be a symptom of another disease. But there are certain parts where if you see a bump then that can be an indication of a tumor in your betta.

Lumps on the head of your betta

One very common place where the bump occurs is on the head of the fish. This can be a brain tumor but yet still it cannot. Lumps like these are also caused by a bacterial infection known as Columnaris. This is found near the fish’s gills and mouth.

Tumor on the Side of the Betta’s Body

lumps that occur on the side of the body are less likely to be tumors. It’s not that the tumor cannot emerge there, it’s just that bumps on the side of fish’s bodies can be other conditions as well which can be treated. They can be:

Swim Bladder Disease

If your fish lumps on the side of its body then there are likely chances that it swims balder just like it can be a tumor. The swim bladder is an internal sac that is filled with air and helps the fish to maintain its balance underwater and helps it to swim properly. Fish that are affected by swim bladder infection may not be able to swim properly, they may lose their appetite, is more lethargic than their usual self, their body is swollen, and they may be swimming alongside. This happens when the fish has been overeating or is constipated. You can easily treat this disease by using the three-day fasting method, and by limiting the amount of food given to the fish.


Other than tumors dropsy can also be formed in your fish. This disease is much more dangerous than a tumor. Your fish may live a while longer when it has a tumor but when it is affected with dropsy there is no chance of it surviving. Unless the disease is caught beforehand and the treatment is started right away. Betta infected with dropsy also appears bloated with more like a pinecone-shaped body, curved spine, and protruding scales. Although you can use antibiotics to cure the disease its prognosis is very low.

Bacterial Infection

Lastly, we have the bacterial infection that can develop when a fish has an open wound or a weak immune system making it more prone to bacterial attack. These wounds can turn into lumps upon bacteria intruding on the fish’s body and turn into abscesses as mentioned above.

Tumor on Betta’s Stomach

The last most common place where a bump is usually on the stomach of the fish. This can be a tumor, but also not. It could be dropsy, swim bladder disease, bacterial infection, or even constipation.


This is very common among betta fish. They can develop a bump on their stomach, this bump is not usually infected, rather it is blasting within the fish due to overconsumption of food. This disease is easily treatable. You can use the three-day fasting method to solve this problem, or you could also use frozen food or the inside of a boiled pea to get rid of this infection quickly.

Tumor in Betta Fish Gills

If you notice a bump on your fish’s gills then it can be hyperplasia. This occurs when the gills have been damaged due to any parasitic attack, bacterial infection, or any physical injury, or it can even occur due to toxins such as ammonia, nitrates, or nitrites. So how the bump forms are that rather than the gill healing completely the damaged tissues form a layer of skin above it, which causes a bump similar to a tumor. The bump grows as there is more skin forming. But the severe cases are that the bump can remain permanent or in minor cases, the bump disappears over time.

Treatment of Tumors in Betta

There are no such tumors in betta. It is not treatable, but if you see your fish swimming normally around the tank then let it live. However, in the worst cases when they feel a lot of pain it’s time to euthanize them. There are some cases where people were successful in treating tumors through surgeries on their betta, but its chances of success are very low and it might cause extra suffering for your fish.

How to Prevent Tumors in Betta?

It completely depends upon the genetics of your betta on whether it will be able to survive the tumor. Here are some ways you can prevent that from happening to your fish:

Buy your fish from a reputable breeder, because some companies inbreed their fish rather than importing or rearing bettas properly as that is way cheaper for them. Thus, inbred fishes are more likely to come with a whole lot of problems inclusive of cancerous tumors in them.

Keep the water clean at all times and maintain an efficient filtration system. Try making sure that you clean 25%of water every week to prevent the bacteria from building up, which can lead to health problems for your betta.

Feed your fish high-quality food, as low-quality food does not include high levels of nutrients and protein that help your fish maintain a healthy life.

Treat other infections quickly, if not then the immune system weakens and makes your betta more prone to other diseases and infections. It is best to start treatment right away before letting your fish catch any other disease.

Place the infected fish in a separate tank, you should quarantine the infected fish separately as it reduces the chances of spreading the disease to other fishes in the main tank. this will also make it easier to treat the disease.

The Bottom Line on Betta Fish Tumor

Cancerous tumors can appear in your fish, but bumps and lumps do not always assure that the fish has a tumor. It can be anything that is causing those lumps as mentioned above in detail. So don’t always jump to conclusions rather first look for yourself for the symptoms, and then diagnose your betta with the disease. Make sure to use all the prevention methods and the right treatments for the diseases.

Always keep a check on your fish’s tank to see for any changes in your fish behavior, because if the disease is spotted early then the chances of its cure are high and you can get your fish to live a healthy life again.

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