Betta fish tumor causes and cures of the betta fish abnormal lumpsBetta fish tumor can be quite disturbing, especially to an amateur aquarist. With little or no experience, it would be difficult to tell if swelling is fatal and how to make it go away. However, you don’t need to panic right away, as the swelling is most likely an abscess or an ulcer.

Nonetheless, keep reading to learn how to prevent a tumor and what to do when you notice a tumor on your Betta fish.

What Causes Tumors in the Betta Fish?

Like humans, some Bettas are susceptible to getting cancerous tumors even while living under pristine conditions. Note that, if a healthy Betta starts to develop tumors, it’s best to scrutinize the Betta’s care routine for adverse factors like:

  • Poor diet
  • Viral infections
  • Poor living conditions

– Why Does My Betta Fish Have Tumors in Its Gills?

A tumor in the Betta fish gills can be a symptom of gill hyperplasia. Gill hyperplasia is damage caused by physical injury, parasites, bacterial infections, or toxins (nitrites, ammonia, and nitrate) present in the aquarium water. In this case, a new tissue begins to develop over the damaged gills instead of healing correctly.

In addition, if it is not treated, it would continue to grow into an enormous lump. In minor hyperplasia cases, the growth is reversible. It goes away on its own, and the gill goes back to normalcy, but for severe circumstances, it becomes permanent.

How To Prevent the Betta Fish From Developing Tumors?

If a Betta fish is not genetically prone to developing tumors, you can prevent lumps with the following tips.

1. Reliable Source

Where you buy your fish is the foundational basis that tells you if your fish would lead a healthy life. Reputable breeders take ethical and intentional steps to ensure their products are of premium quality.

Note that, others would consider a cheaper route and inbreed poor sickly stock. Hence, look out for honest reviews from your chosen source, or you may notice a lump on the  Betta fish or other complications after purchase.

2. Adequate Living Conditions

Cleaning the Betta fish tank, changing its water, and installing a good filter are great ways to prevent tumors. Pristine conditions prevent bacteria build-up and keep the fish healthy.

3. High-Quality Diet

You should give Bettas high-quality food because it contains the right proportion of the nutrients they require to remain healthy.

4. Isolation

Closely monitor the Betta fish, so you can take out the sick fish and quarantine it if you notice any strange symptoms. This method would help halt a possible outbreak, and you can focus on adequately treating the sick fish.

Locating Tumors

Below are some common locations you can find tumors on the Betta fish body.

  • Head
  • Side
  • Stomach
  • Gills

However, finding a random white bump on Betta fish does not mean it is a tumor, as tumors would not develop on every body part.

Euthanizing a Betta Fish With Tumors

Euthanizing is a hard decision to make for most fish keepers, but it’s important to recognize when it is best to let go. If you can tell that the fish is in pain with the Betta fish and unhappy, then it may be time. To euthanize the fish, you can use the MS-222(Fin-quel). Unlike the popular suggestions of using alcohol or clove oil, it is a humane method.

Clove oil has no accurate measurement, while alcohol burns the Betta gills and internal organs until it dies. Nonetheless, speak to a vet doctor if you decide to euthanize your Betta fish.

Bump on the Betta’s Side

Although a Betta fish bump on side could be due to a cancerous tumor, it may also be a mild diagnosis. There are various other reasons a Betta fish could have a bumpy side, and fortunately, most are usually treatable. Here are a few of them.

– Swim Bladder Disease

Swim bladder disease occurs when the fish swim bladder is infected. A swim bladder is a gas-filled sac in the fish that aids with buoyancy and swimming. Also, the disorder causes the fish to become swollen and sluggish.

The affected fish would involuntarily sink to the bottom or remain at the top of the water surface. Other times, the fish will struggle to remain stable in the tank. It may have to adapt to a crooked swimming posture to move around the aquarium.

Overfeeding and constipation are significant causes of swim bladder disease. The disease is not infectious, hence you do not need to isolate the Betta fish. However, you can get rid of the swim bladder disease by starving the fish for a few days.

Its digestive system needs time to process the remaining food and revert back to normal. Alternatively, there are over-the-counter medications that give faster relief to the swim bladder problem. You can treat the infection by following the product dosage recommendation.

– Dropsy

Dropsy is a severe bacterial infection that affects the Betta fish kidney as a result of unsanitary living conditions. It causes the fish to retain fluid, become bloated and eventually leads to renal failure. Additionally, the fish spine would become curved, and in the final stage of the dropsy disease, the fish would have protruding scales. Undeniably, dropsy can be cured in Betta fish, but the chances of fatality are very high.

– Bacterial Infections

A Betta fish with a side injury caused by sharp tank surfaces or tank mates can develop an abscess due to bacterial infections.

– Difference Between a Fungi or Bacteria Tumor

A bacteria tumor is usually a solid white growth on Betta fish.  While a tumor caused by fungal infections would be accompanied by scale discoloration, and it is porous like cotton. Nevertheless, they are all similar at first glance but are pretty different.

On the other hand, a Betta fish cancer tumor is uncommon; it can be an external or internal swelling on the fish skin. However, we advise you to rule out the possibility of it just being an abscess or an ulcer.


1. Does a Tumor Mean My Betta Fish Would Die?

The answer is no, not all tumors are fatal, but it is also hard to tell if the Betta fish would survive it. In addition, there’s no straightforward cure for tumors in Betta fish. If the fish seems well, can still move around, and seems to eat properly, you may leave the growth alone. The fish may live a full life for many years with it.

On the other hand, you may have a vet cut them out and closely monitor the quality of life you offer your fish. But in extreme cases, especially if the fish seems to be in constant pain, you would have to consider euthanizing it.

2. How Do I Recognize a Betta Fish Abscess?

You can easily recognize an abscess because it appears like a white tumor on Betta fish body. They are caused when a bacterial infection gets into the fish. For instance, the fish should heal just fine after a slight injury from a scratch or nip from a tank mate. But if the tank is dirty, bacteria could get into the body of the fish through this open wound.

The bacteria would then destroy the surrounding tissues at the injury site, and its decomposing matter would form pus. This pus would gather under the fish’s skin resulting in an abscess or lump. Note that if it is not treated, it would continue to swell until it burst open, causing a bigger sore. Hence, this would leave the Betta fish vulnerable to another bacteria-abscess cycle.

3. How To Treat a Betta Fish Ulcer?

As soon as you notice an ulcer on the Betta fish, you should first isolate it in a quarantine tank. Make sure the tank is clean, and you perform frequent water changes. Using the measurement of 0.2447 Ounces of salt to one gallon of water slightly increases the tank’s salinity as it helps the wound heal faster. Continue this for 14-21 days and even after the ulcer heals to prevent fungal infestation.

The salt would act as a mild disinfectant and help reduce the water’s osmotic effect. You can maintain the tank water salinity after water changes by re-adding in 30 percent of the original salt measurement. Alternatively, you can monitor the salt content with a hydrometer. Likewise, add an antibacterial medication into the water.

4. How To Treat the Betta Fish Abscess

A Betta fish abscess should be treated immediately you notice it; first, take out the fish and quarantine it. The Betta fish has a higher chance of surviving a small-sized abscess than a big one. Additionally, you can tackle the bacteria infection by adding aquarium antibacterial medication to the tank. Make sure to follow the recommended dosage prescribed by the product manufacturer.

In addition, you can improve recovery speed by making the Betta fish comfortable. Closely monitor the fish, perform frequent water changes and clean the tank. Moreover, the tank should have good water quality, a good filtration system, lighting, and shade to hide.

Below are other tank decorations to consider when putting together a quarantine tank.

– Cave

A cave would give the sick fish a place to hide when stressed; also, it should be similar to the type in its main tank. Hence, a partially buried smooth-sided flower pot would do. It would help the Betta fish feel safe when vulnerable, also it is a budget-friendly tip.

– Plants

Although fresh plants increase the oxygen content in the aquarium, they are also likely sources of bacteria. They can harbor parasites which can cause further harm to the fish. However, the fish needs plants in its tank because they serve as hiding places. Therefore, opt for artificial instead of fresh ones.

5. Why Does My Betta Fish Have Lumps on Its Stomach?

Lump on Betta fish stomach is not surprising. Like the bumps on the Betta fish side, constipation, dropsy, swim bladder infection, and bacterial infection can also cause the fish stomach to swell. Below are a few symptoms and cures of a constipated Betta fish.

Constipation causes a lumpy stomach in the Betta fish and can be treated. Therefore, if you are wondering if your Betta fish is constipated, here are some symptoms.

  • Appetite loss
  • Sluggishness
  • The fish would not defecate.

You can cure this disorder by not feeding the fish for some days. Then, offer them frozen or live blood worms afterward to reset their digestive system. This would effectively get rid of any blockage without using any medication. Furthermore, you can incorporate a one-day-fast weekly to reduce the likely occurrence of constipation in your fish.

6. How Do I Know if My Betta Fish Has a Tumor?

A Betta fish can have different lumps or bumps under or on its skin, but not all are tumors. Some tumors may be pretty huge, while others may be tiny. Have in mind that, big tumors affect the buoyancy of the fish and its potential to swim appropriately. Furthermore, other symptoms you should look out for are loss of appetite and lethargy in your fish.

7. What Are the Types of Betta Fish Tumors?

The major types of Betta fish tumors are benign and cancerous tumors. Although tumors may look like every other lumpy swelling or growth on the Betta fish skin, however, every lump differs. Benign tumors, for instance, remain at a particular part of the Betta’s body while the malignant tumor spreads.

The malignant or cancerous tumors would rapidly replicate on surrounding tissue and even extend to other parts! Similarly, certain bacteria and viruses can also cause these abnormal growths on the Betta fish skin. Nevertheless, a Betta fish is likely to develop tumors on their skin and reproductive organs even though they grow on almost any tissue.

8. Can You Treat All Betta Fish Tumors?

No, not all Betta fish tumors can be treated. Internal tumors, for instance, may not be easily recognized. This is because the fish may be exhibiting symptoms that are also synonymous with other illnesses. Yet, if you are unsure, invite a vet doctor immediately you detect any strange sign.

Furthermore, Betta fish cancer tumors may be surgically removed. But, the surgery should be conducted only by a qualified veterinary surgeon with experience in tropical fish treatments. Even so, the success rate is low, and there’s no guarantee that the Betta fish tumor will not reoccur.

9. Can Betta Fish Tumors Grow Internally?

Yes, not all tumors grow on the Betta fish body surface. Some tumors cannot be detected with bare eyes as they are internal. However, these types of tumors can be pretty severe as they may be spotted late.

Sadly, in this case, the fish’s health would continually deteriorate, and you may not be able to stop it. Hence, you would have to consider euthanizing the fish as a last resort.

10. Why Does My Betta Fish Have a Lump on Its Head?

A Betta fish tumor on the head is pretty common, this lump on the  Betta fish may be a cancer tumor or a bacterial infection. Columnaris is the bacteria responsible for the lumpy lesions if diagnosed as the latter. It appears around the fish’s gills and mouth.

Furthermore, parasitic or bacterial growth from a Betta velvet infection can also cause a head abscess. Nevertheless, if it is a cancerous head tumor, it is a fatal diagnosis. It will cause the fish so much distress if you try to surgical remove it.

Betta fish tumor11. How Do I Recognize a Betta Fish Ulcer?

Fish ulcers appear like common bumps on the Betta fish skin, but you can easily detect them, as they are caused by bacterial infections. The ulcers appear sore and appear reddish around the lumpy edges. On the other hand, the fish exhibit lethargic symptoms and lose so much weight until they completely stop eating.

You see, a healthy aquarium contains a fair amount of bacteria and would not harm a healthy fish. Moreover, if the fish becomes stressed by unfavorable environmental factors, they become weak. A vulnerable fish is susceptible to bacteria attack, leading to ulcers.


You see, cancerous tumors happen to Betta fish but are pretty rare, hence if you keep their aquarium clean and feed them well, you can avoid a tumor scare. Here are some essential tips we should remember:

  • Not all lumps found on the Betta fish body are tumors
  • A tumor on the Betta head can be a Betta velvet bacterial infection
  • A tumor on a Betta fish side can be an abscess
  • A tumor on the Betta fish stomach can be constipation

Owning a Betta fish with a tumor does not have to be complicated, understand that there is no straightforward tumor cure, but still, you may have to consider surgery or euthanizing the Betta fish. However, in the end, your choice should boil down to ensuring your Betta fish remains comfortable and happy.

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