7 Causes of Betta Fish Ulcer: Symptoms and Treatment

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Most Betta fish ulcers are secondary to some other stressors. So what is the cause of the ulcer? It must be identified. Otherwise, the ulcer will return, no matter what treatment you use. Dr. Jessie Sanders a veterinarian by profession, said the words.

Betta fish ulcers are a concern for every pet owner. However, by taking some simple precautions, it can be prevented. Good water quality and healthy food are the best preventatives of ulcers in betta fish.

This article will discuss the causes, symptoms, and treatment of betta fish ulcers. To know in detail, read this post till the end.

What is an ulcer on Betta fish?

According to thesprucepets, ulcers are skin lesions in fish that result in tissue necrosis. This exposes the underlying muscles. An ulcer on the abdomen may expose internal organs. Deeper ulcers are more likely to kill fish.

The scales of the fish fall off, and pinkish-red or whitish lesions appear. This indicates that the fish’s immune system is weakened. Ulcers cause significant discomfort and stress to the fish, and even death is inevitable if not treated in time.

Ulcerated fish have red spots around the wound. Affected fish lose appetite, become lethargic, and swim abnormally.

Symptoms of Ulcers in Betta Fish

Check your betta fish carefully and see if it exhibits any of the symptoms. However, not all symptoms will appear at the same time. Different fish will show different symptoms.

  • Elevation of fish scales and formation of lesions
  • Red or pink spots around the wound area.
  • Loss of mucus around the skin
  • Exposure of underlying muscles and organs
  • Increased redness to veins
  • Broken fins
  • Pineconing
  • Skin erosion
  • Loss of appetite
  • Sluggishness or lethargy
  • Swim abnormally
  • Death of fish

If you realize that your betta fish has an ulcer, start treatment immediately. Otherwise, your fish will get sicker and die. If you are unsure whether your betta fish has an ulcer, contact a veterinarian immediately and follow his advice.

How to Diagnosis of Betta Fish Ulcer

If you want to be sure if your betta fish has ulcers, consult your veterinarian. He or she can confirm whether your betta fish has an ulcer by performing a bacterial culture and antibiotic sensitivity test.
If infected, he will prescribe how your betta fish will recover quickly.

Causes of Ulcers in Betta Fish?

There are many causes of ulcers in betta fish. However, most of these causes are easily fixable. You don’t have to work hard for it. Causes of ulcers in betta fish include:

1. Poor Water Quality

Poor water quality is one of the main causes of ulcers in betta fish. Many betta owners do not change the water regularly. They also neglected to clean the tank. Regular tank maintenance is very important for the health of betta fish. If not maintained regularly, your Betta fish can suffer from various diseases, including ulcers. Also, the presence of ammonia and other toxic substances in the aquarium water needs to be checked regularly.

Here is a table of the best water parameters for betta fish:

ParameterOptimal Range
Temperature 78-80°F (25.5-26.5°C)
pH Level 6.5-7.5
Ammonia (NH3/NH4+) 0 ppm
Nitrite (NO2-) 0 ppm
Nitrate (NO3-) < 20 ppm
Hardness (GH) 3-4 dGH (50-66.7 ppm)
Alkalinity (KH) 3-5 dKH (53.6- 89.4 ppm)
Water parameters for betta fish

2. Bacterial or Fungal Infections

Another cause of ulcers in betta fish is bacterial and fungal infections. However, if the fish’s immune system is good, the bacteria cannot harm them. But when the immune system becomes weak, then the bacteria start to affect the fish.

Poor water quality and malnutrition are responsible for weakening the fish’s immune system. Always keep the betta fish tank clean and change the water regularly. Feed the fish the nutrients they need. Never overfeed or underfeed.

3. Ulcers in betta fish due to parasites

Betta fish are tropical freshwater fish. Parasites nest in the fish’s body and start damaging the skin. They can take shelter both inside and outside the fish’s body. Due to skin parasites, the body of the fish starts itching. This results in the fish scratching themselves on the aquarium walls or decorations. This behavior also results in the formation of wounds on the body of the fish.

Parasites enter the aquarium by introducing new fish without quarantine. So be sure to quarantine them before adding anything new to the aquarium. Also, maintain the correct water temperature. This will cause the parasites to fail to complete their life cycle.

4. Injuries can cause betta fish ulcers

Sometimes betta fish are injured by hitting the edge of the aquarium decoration or rocks, which can cause wounds on the betta fish. Due to the injury, the body or fins of the fish are often severed. As a result, their immunity decreases, which is one of the causes of ulcers.

Do not put any sharp objects in your betta fish tank that could injure the betta fish.

5. Poor Nutrition

Malnutrition weakens the betta fish’s immune system. Weakfish can easily become sick or diseased. Malnourished fish can easily develop ulcers.

Betta fish are carnivores. They need a diet rich in protein. Understand the basic dietary needs of betta fish and feed them accordingly.


6. Attacked by an aggressive tank mate

Many times, aggressive tankmates injure the fish. However, the Betta fish itself is aggressive and prefers to live alone. Sometimes tankmates can attack and injure them. Injured fish can easily develop ulcers. So experts recommend keeping only one betta fish in an aquarium.

If you want your betta fish to have tank mates, choose mates that are not aggressive.

7. Stress

Betta fish are easily stressed. Betta fish can be stressed for several reasons, including poor water quality, inadequate habitat, or aggression by other fish.

Stress can weaken the fish’s immune system. Due to this, ulcer infection and other diseases make their home in the fish body.

What Do Ulcers Look Like on Fish?

There are different types of ulcers. However, they usually appear as open sores or lesions on the fish’s skin or fins.

Sometimes, the ulcer is covered with a white or gray lining. If this is the case, it is a sign of a secondary bacterial or fungal infection.

Ulcers vary in size from small to large and are round or irregular in appearance.

In some cases, the gills become pale due to ulcers.

Due to ulcers, deep wounds can be created in the fish’s body.

In some cases, the area around the fish’s eyes swells, and the eyes appear enlarged.

Treatment of Ulcers in Betta Fish

What is the cause of betta fish ulcers? It needs to be diagnosed first for treatment. We have already discussed the reasons why ulcers can occur. If you read them well, it will be easier for you to treat Betta fish ulcers.

Treatment of Betta Fish Ulcer

Maintain and improve proper water parameters

If your betta fish is suffering from ulcers, then first check the water parameters of the tank.

Betta is a tropical fish. They need warm water to thrive, grow, or live healthily. A temperature of 78-80°F is ideal for them.

If the tank is dirty, clean it and change the water

If the ulcer is at an early stage, it will heal on its own with the right water parameters.

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Reduce Stress On Your Betta Fish

Place your betta fish in a tank with plenty of room to swim. Also, have a hiding place in the tank. These will keep him stress-free.

Many times, Betta fish feel stressed due to attacks from tankmates. If your betta fish tank has any fish or animals that constantly attack your betta fish, quickly move those fish or animals away.

Place ulcerated fish in a quarantine tank

If there is more than one fish in a betta tank, move the ulcerated fish to another tank. Prepare a quarantine tank. Leave it there and treat the affected fish.

Use of antibacterial and antifungal medications

If, the ulcer is caused by a bacterial or fungal infection, antibiotics and antifungal medications may be needed to treat the infection.

Do not use over-the-counter antibiotics to treat ulcers in your betta fish.
In most cases, the potency and effectiveness of these products are not tested.

Consult an experienced veterinarian for severe ulcers

If the ulcer becomes too large, a veterinarian must be consulted. The vet can perform some tests to determine the actual cause of the disease and treat your fish accordingly with medication. He can even inject the fish with antibiotics if needed or prescribe fish food with antibiotics.

How to prevent ulcers in Betta Fish?

Preventing ulcers and other diseases is very important to keeping your betta fish healthy. Betta fish need to take some precautions to prevent ulcer infections.

  1. Maintain proper water parameters: Always keep the tank clean. Change half the water in the tank at least once a week. Try to remove uneaten fish food and debris daily. It will have good water parameters. Also, if possible, it is better to check water pH, nitrite, and other parameters regularly with a water test kit.

2. Provide a balanced, fresh diet: Betta fish are carnivores. They need food that is rich in protein. Pellets and flakes specially formulated for betta fish are best for them. Also, they should be fed live food once or twice a week.

Foods that betta fish eat in nature are:

  • Mosquito larvae
  • Brine shrimp
  • Water flies such as Daphnia
  • Crustacean Larvae
  • Deer fly larvae
  • Rice seed midge larvae
  • Bloodworms

3. Quarantine before adding anything to the tank: Adding anything to the tank can introduce bacteria, viruses, or parasites, especially through live food or fish. These parasitic viruses and bacteria infect the fish’s body and cause ulcers by forming lesions. Therefore, before adding anything to the tank, quarantine and clean it thoroughly to prevent ulcers.

4. Protect from injury: Do not place any sharp objects or accessories in the tank. Many times, the fish can get hurt by bumping into those objects. This injury later turns into an ulcer. That is why it is better to avoid such things to prevent ulcers.

5. Keep the fish free of stress: To keep betta fish stress-free, they should be kept in a large tank where they have enough room to swim. Also, loud noise can stress betta fish. In addition, shocks and high currents can also cause stress on the fish. That is why care should be taken so that the water in the tank does not flow too much. And it should be kept in a sound-free place.

How do I heal my betta fish ulcer quickly?

Many people want to know how to cure betta fish ulcers quickly. There is no short answer to this. It depends on the cause of the ulcer and how deep the wound is. An experienced vet should be contacted for quick healing.

If a bacterial or fungal infection is the cause of the ulcer, prompt treatment with antibiotics or antifungals is likely to cure the ulcer. If the ulcer is caused by poor water quality or pressure, it needs to be fixed first.

Place ulcerated fish in a tank with a heater. Slightly warmer water is ideal for betta fish. The tank should have a filter that keeps the tank clean at all times. But it must be ensured that the water flow is not too high because of the filter. Tank size should be 5-10 gallons.


Medicines should be used after a proper diagnosis and knowing the cause of the ulcer. If the ulcer is caused by a bacterial infection, antibiotics such as kanamycin, tetracycline, or nitrofurazone are used.

Fungal infections are treated with antifungal medications such as methylene blue or clotrimazole. In some cases, treatment of ulcers may require a combination of antibiotics and antifungals.

An aquarium specialist or veterinarian should be consulted for proper diagnosis, medication, and dosage. Otherwise, your fish may be damaged due to the wrong treatment.

Can fish ulcers heal on their own?

Some ulcers heal on their own. For example, if you identify a betta fish ulcer caused by unclean water, clean the tank well, and create a healthy environment for the betta fish, the ulcer will probably heal. However, in cases of severe ulcers, medicines should be used as advised by an experienced veterinarian.

How long do betta fish ulcers take to heal?

Minor ulcers can heal very quickly if the cause of the ulcer is diagnosed and treated accordingly. This may take one to two weeks. However, in the case of severe ulcers, the ulcer is likely to heal within 5-6 weeks if treated as the vet recommends.

Q: Can aquarium salt be used to treat ulcers?

Ans: In a separate tank, mix one tablespoon of aquarium salt with three gallons of water. Leave the ulcer-affected month in this for 10 to 15 minutes. Do this for 4/5 consecutive days. It is a good way to cure parasitic, bacterial, and other fungal infections. This will help to reduce the scarring caused by ulcers.

Q: Are there any natural remedies for betta fish ulcers?

Ans: Natural remedies, including salt baths and herbal additives, can complement traditional medications in treating betta fish ulcers. However, consulting a vet for a tailored treatment plan is crucial.

Q: Can betta fish ulcers be contagious to other fish?

Ans: Yes, betta fish ulcers can be transmitted to other fish. For this reason, fish with ulcers should be kept in a separate place and treated.

Q: Can trauma cause ulcers in betta fish?

Ans: If a Betta fish gets a wound from a sharp object or an attack from another fish and it is left untreated, it is likely to develop an ulcer.

Q: How does stress cause betta fish ulcers?

Ans: Stress weakens the fish’s immune system. A weak person can easily get ulcers and other diseases.


You can prevent ulcers in your betta fish with some simple care. The truth is that prevention is better than cure. Regular tank cleaning and water changes, feeding nutritious food, and reducing fish stress help keep the fish healthy.

If, for some reason, your betta fish has developed an ulcer, do not delay in starting treatment. Consult a fish specialist or veterinarian for treatment of any fish disease, including ulcers.

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