15 Betta Fish Diseases & Their Treatments: A Complete Guide

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Keeping Betta fish in my aquarium has been an enlightening journey. These vibrant swimmers are not only visually stunning but also relatively easy to maintain.

However, as with any living creature, they’re prone to health problems, and that’s where my role becomes crucial.

Addressing the health concerns of fish is somewhat of an art form, especially for Bettas with their distinct characteristics.

This inspired me to create this guide.

In it, I delve into 15 typical health issues Betta fish may face, along with thoroughly researched solutions for each.

Let’s dive in.

Also Read: Betta Fish Care Guide

1. Fin Rot

Fin Rot in betta fish is a bacterial infection that primarily affects the fins and tails, causing them to fray, discolor, or even rot away.

Poor water quality, stress, and injury can make bettas susceptible to this condition. If not addressed, fin rot can progress to the body, posing a serious health risk.


  • Fins or tail appear torn or frayed
  • Discoloration or redness at the edges of fins
  • Whitish or milky appearance at the base of fins
  • Reduced activity or appetite
  • Fins progressively shortening or deteriorating


  • Perform a 50% water change immediately and continue with 20% changes daily to improve water quality.
  • Apply a broad-spectrum antibiotic like erythromycin, following the dosage of 200-400 mg per 10 gallons of water. Continue treatment for 5-7 days.
  • Add aquarium salt at a rate of 1 teaspoon per gallon to aid fin regeneration. Avoid overuse, especially in soft water.
  • Isolate the betta if in a community tank to prevent stress and further infection. Ensure a stress-free environment with optimal temperature (78-80°F) and pH (6.5-7.5).

Also Read: Curled and Clamped Betta Fins

2. Ich (White Spot Disease)

Ich, or White Spot Disease, is caused by the parasite Ichthyophthirius multifiliis, appearing as small, white spots on a betta fish’s body and fins.

It’s highly contagious and can be fatal if not treated promptly. The parasite burrows into the fish’s skin, causing irritation and vulnerability to secondary infections.


  • White, salt-like spots on skin and fins
  • Scratching against objects in the aquarium
  • Clamped fins
  • Lethargy and decreased appetite
  • Rapid gill movements or difficulty breathing


  • Raise the tank temperature to 82°F gradually over 24 hours to speed up the parasite’s lifecycle.
  • Treat with a copper-based medication like Coppersafe (link to Amazon), dosing 2 ml per 4 gallons of water, for a minimum of 10 days.
  • Perform daily 25% water changes to remove parasites from the water.
  • Supplement with a half dose of aquarium salt (1/2 teaspoon per gallon) to aid the fish’s recovery, but monitor for any signs of stress.

Also Read: Betta Fish Rubbing

3. Velvet Disease

Velvet Disease, caused by the dinoflagellate Piscinoodinium pillulare, presents as a rusty or gold dusting on the betta’s body and is often accompanied by respiratory distress.

It is highly infectious and can be fatal if not treated quickly. The parasite attacks the gills and skin, impairing the fish’s ability to breathe.


  • Gold or rust-colored dusting on skin
  • Scratching against tank decorations or substrate
  • Clamped fins
  • Rapid gill movement
  • Lethargy and loss of appetite


  • Dim or turn off the tank lights as the parasite thrives in light.
  • Treat with a copper-based medication like CopperSafe, administering 2 ml per 4 gallons of water. Continue treatment for at least 10 days.
  • Increase the water temperature to about 82°F to speed up the parasite’s life cycle.
  • Conduct daily 25% water changes to help remove free-floating parasites and improve overall water conditions.

4. Popeye

Popeye in betta fish is usually a symptom of an underlying bacterial infection, causing the eyes to bulge out due to fluid buildup.

It can result from poor water quality, injury, or internal infection. Severe cases of popeye can lead to blindness or even loss of the affected eye.


  • One or both eyes protruding unusually
  • Cloudiness or haziness in the affected eye
  • Swelling around the eye
  • Changes in swimming behavior or appetite
  • Inactivity or hiding more than usual


  • Perform a 50% water change immediately, followed by 20% daily changes to improve water quality.
  • Treat with an antibiotic like Kanamycin, dosing 500 mg per 20 gallons of water. Continue for 5-7 days.
  • Add Epsom salt at a rate of 1/8 teaspoon per 5 gallons to reduce swelling. Dissolve the salt in tank water before adding.
  • Isolate the fish in a hospital tank and maintain optimal water conditions (temperature around 78°F, pH 6.5-7.5) to reduce stress and prevent further injury.

5. Dropsy

Dropsy in betta fish is not a disease itself but a symptom of a more serious underlying condition, often related to kidney failure or bacterial infection.

It is characterized by a swollen body and protruding scales, resembling a pinecone. This condition is generally difficult to treat and can be fatal if not addressed promptly.


  • Swollen or bloated body
  • Scales sticking outwards, resembling a pinecone
  • Pale or discolored feces
  • Lethargy and loss of appetite
  • Floating or sinking abnormally


  • Quarantine the affected fish to prevent the spread of any potential infection.
  • Treat with a broad-spectrum antibiotic like Kanamycin, dosing at 500 mg per 20 gallons of water for 7-10 days.
  • Add Epsom salt at a rate of 1/8 teaspoon per 5 gallons of water to help reduce swelling and improve kidney function. Dissolve it thoroughly before adding to the tank.
  • Ensure pristine water conditions with regular water changes and maintain a balanced diet to support the fish’s immune system.

6. Swim Bladder Disorder

Swim Bladder Disorder in betta fish is typically caused by issues with the swim bladder, affecting the fish’s ability to control its buoyancy.

It can result from overfeeding, constipation, or infection. Affected fish might float uncontrollably, sink to the bottom, or struggle to maintain a normal position.


  • Difficulty swimming or maintaining balance
  • Floating at the top or sinking to the bottom
  • Swollen belly
  • Inactivity or lethargy
  • Curved back or abnormal vertical posture


  • Fast the fish for 2-3 days to relieve constipation, followed by feeding a small amount of boiled, skinned pea to aid in digestion.
  • Ensure water quality is optimal with regular changes and maintain water temperature around 78°F.
  • If constipation is not the issue, treat with a broad-spectrum antibiotic in case of a bacterial infection.
  • Reduce stress by providing a calm environment and consider adjusting the water level to make it easier for the fish to swim.

Also Read: Why Is My Betta Fish Upside Down?

7. Fungal Infections

Fungal infections in betta fish often appear as white, cotton-like growths on the skin, mouth, or fins.

These infections can occur due to injury, poor water quality, or a weakened immune system. Without treatment, fungal infections can lead to more severe health issues.


  • White, cotton-like patches on skin, fins, or mouth
  • Discolored or frayed fins
  • Reduced appetite or lethargy
  • Rapid gill movement
  • Ulcers or open sores in severe cases


  • Isolate the affected fish to prevent spreading the infection.
  • Treat with an antifungal medication like Methylene Blue (link to Amazon) or Pimafix, following the dosage instructions on the product label.
  • Perform regular water changes to maintain high water quality.
  • Keep the water temperature consistent, ideally around 78°F, to help the fish’s immune system fight off the infection.

8. Bacterial Infections

Bacterial infections in betta fish can manifest in various ways, including fin rot, popeye, or septicemia, and are often a result of poor water quality or injury.

Symptoms vary but can include discoloration, swelling, and abnormal behavior. These infections can be fatal if left untreated.


  • Red streaks or sores on the body
  • Swollen eyes (popeye)
  • Discolored or frayed fins
  • Rapid breathing or lethargy
  • Loss of appetite


  • Quarantine the fish to prevent the spread of infection.
  • Treat with a broad-spectrum antibiotic like Maracyn or Kanamycin, following the specific dosage instructions for the chosen medication.
  • Improve water quality with regular changes and maintain optimal water temperature and pH levels.
  • Support the fish’s immune system with a balanced diet and a stress-free environment.

9. Columnaris

Columnaris, also known as cotton wool disease, is a bacterial infection caused by Flavobacterium columnare.

It presents as white or grayish patches on the skin, fins, or gills and can rapidly deteriorate the fish’s health. Columnaris is highly contagious and can be fatal if not treated promptly.


  • White or grayish patches on the skin, fins, or gills
  • Ulcers or sores on the body
  • Fins appearing ragged or frayed
  • Rapid gill movement or difficulty breathing
  • Lethargy and loss of appetite


  • Immediately improve water quality with at least a 50% water change and continue with regular changes.
  • Treat with antibiotics such as Kanamycin, dosing 500 mg per 20 gallons of water, combined with Furan-2 following the package instructions, for a minimum of 10 days.
  • Add aquarium salt at a rate of 1 teaspoon per gallon to aid

10. Hole in the Head Disease

Hole in the Head Disease is a condition often seen in betta fish, characterized by pitting or lesions on the head and body.

It’s believed to be caused by a variety of factors, including poor water quality, nutritional deficiencies, and parasites. The condition can progress to more severe health issues if not addressed.


  • Pitting or holes in the head and body
  • Loss of appetite
  • Lethargy or listlessness
  • Faded coloration
  • Mucous or slime production around lesions


  • Improve water quality through frequent water changes and ensure the tank is properly filtered.
  • Offer a balanced diet rich in vitamins and nutrients, possibly supplementing with vitamin C and other nutrients. My recommendation: Seachem Nourish (link to Amazon).
  • Treat with anti-parasitic medication, such as metronidazole, following the recommended dosage for betta fish.
  • Monitor water parameters regularly to prevent recurrence, focusing on stable pH and temperature.

11. Tuberculosis

Fish Tuberculosis is a serious, often fatal condition caused by Mycobacterium marinum. It can be difficult to diagnose as symptoms are varied and can resemble other illnesses.

The disease is zoonotic, meaning it can be transmitted to humans, so handling infected fish or tank water should be done with caution.


  • Emaciation or severe weight loss
  • Curved spine or skeletal deformities
  • Skin ulcers and lesions
  • Loss of appetite and lethargy
  • Abnormal swimming behavior


  • There is no known effective treatment for fish tuberculosis. Euthanasia is often recommended to prevent suffering and contagion.
  • If other fish are in the same tank, monitor them closely for signs of illness.
  • Disinfect the tank, equipment, and anything that came in contact with the infected fish using a bleach solution.
  • Always use gloves and wash hands thoroughly after handling fish or aquarium water.

12. Gill Flukes

Gill Flukes are parasitic flatworms that infect the gills of betta fish, causing respiratory distress and irritation.

They are highly contagious and can spread quickly in a tank environment. Early detection and treatment are crucial for the health of the fish.


  • Rapid or labored breathing
  • Excessive mucus on gills
  • Fish rubbing or scratching against objects
  • Clamped fins
  • Pale gills and lethargy


  • Treat the entire tank with a praziquantel-based medication, such as PraziPro (link to Amazon), following the dosage instructions on the label.
  • Perform partial water changes of 25-30% daily during treatment to remove free-floating parasites and eggs.
  • Increase aeration in the tank to ensure adequate oxygen levels, as affected gills may impair breathing.
  • Maintain clean and optimal water conditions post-treatment to prevent recurrence, including regular monitoring of water parameters.

13. Anchor Worms

Anchor Worms are parasitic crustaceans that attach to the skin, fins, or gills of betta fish. 

They are visible to the naked eye as small, whitish-green threads protruding from the fish’s body.

These parasites can cause significant damage and secondary infections if not promptly treated.


  • Visible thread-like worms attached to the fish’s body
  • Redness or inflammation at the attachment site
  • Scratching or rubbing against objects in the tank
  • Fins may appear clamped or damaged
  • Lethargy or reduced appetite


  • Manually remove visible worms using tweezers, being extremely careful not to harm the fish.
  • Treat the tank with an anti-parasitic medication such as Dimilin or a cypermethrin-based treatment, following the manufacturer’s instructions.
  • Perform frequent water changes (25-30% daily) to remove eggs and larvae.
  • Add aquarium salt at a rate of 1 teaspoon per gallon to aid healing and stress reduction.

Also Read: Betta Fish Eggs Care

14. Fish Lice

Fish Lice, also known as Argulus, are a type of crustacean parasite that attach to the skin of betta fish. They are visible as small, disk-shaped organisms on the fish’s body.

Fish lice can cause irritation, damage to the skin, and potentially lead to secondary infections.


  • Visible disc-shaped parasites on the fish’s skin
  • Redness or irritation at the site of attachment
  • Scratching or rubbing against tank surfaces
  • Lethargy or abnormal swimming
  • Decreased appetite


  • Physically remove the lice using fine tweezers or a similar tool. Be gentle to avoid injuring the fish.
  • Treat the tank with an anti-parasitic medication like Dimilin or a cypermethrin-based treatment, as per the product’s dosage instructions.
  • Conduct regular water changes (25-30% daily) to remove any larvae and prevent re-infestation.
  • Maintain optimal water conditions and reduce stress by providing a well-maintained, stable environment.

15. Septicemia

Septicemia in betta fish is a systemic bacterial infection that can affect multiple organs and tissues.

It is characterized by blood poisoning and is often caused by poor water quality or untreated injuries. Symptoms can vary, but it is a serious condition that requires immediate attention.


  • Red streaks or blotches on the body or fins
  • Swollen or bloated abdomen
  • Ulcers or open sores on the body
  • Lethargic behavior and loss of appetite
  • Rapid breathing or gill discoloration


  • Quarantine the affected fish to a hospital tank to prevent the spread of infection.
  • Treat with a broad-spectrum antibiotic like Kanamycin or Tetracycline, following the recommended dosage for betta fish.
  • Perform regular water changes (at least 20-30% daily) in both the hospital and main tank to improve water quality.
  • Ensure a stress-free environment with optimal water temperature (around 78°F) and pH levels, and provide a nutritious diet to support the fish’s immune system.

Which Disease Is Most Common in Betta Fish?

Fin rot frequently affects betta fish, primarily due to its link with environmental factors.

This disease is indicative of broader issues in tank maintenance, such as inadequate filtration or irregular water changes.

Its prevalence underscores the importance of regular care and monitoring of water conditions in betta habitats.

Tips for Maintaining an Ideal Hospital Tank for Bettas

Setting up a hospital tank for bettas is essential for effective treatment and recovery.

It should be a stable, controlled environment that caters to the specific needs of a sick betta fish.

  • Appropriate Size: A hospital tank should be at least 5 gallons to provide sufficient space for the betta to move comfortably, while being manageable for treatment and water changes.
  • Stable Water Parameters: Maintain the water temperature between 76-80°F and pH levels around 7.0, using a heater and testing kits to monitor conditions regularly.
  • Minimal Decor: Keep the tank bare with minimal decorations to avoid injury and make it easier to clean, though a small hideout can provide a sense of security.
  • Filtered But Gentle: Use a sponge filter to keep the water clean without creating strong currents, as sick bettas often struggle with swimming.

Are Betta Fish Prone to Disease?

Betta fish can be prone to diseases, especially when exposed to stressors like fluctuating water temperatures, overcrowding, or poor diet.

Their susceptibility is often heightened in captivity, where conditions can deviate from their natural habitat.

Proper tank management, including stable water conditions and a nutritious diet, is crucial in reducing their risk of illness.

Also Read: Stress In Betta Fish

In Which Diseases Is It Best to Isolate My Betta?

Isolating your betta fish can be crucial in certain disease scenarios to either prevent the spread of contagious conditions or to provide a more controlled environment for treatment. 

Here are some diseases where isolation is recommended:

  • Fin Rot: Isolation helps prevent the spread to other fish and allows for targeted treatment.
  • Ich (White Spot Disease): Highly contagious; isolation helps manage treatment effectively and stops the spread.
  • Velvet Disease: Like Ich, it’s contagious, and isolating the infected fish allows for more focused treatment.
  • Bacterial Infections: General bacterial infections can spread to other tank mates; isolation aids in effective treatment.
  • Columnaris: Due to its contagious nature, isolating affected fish is important to prevent transmission.
  • Fungal Infections: Isolation helps prevent spread to other fish and can make topical treatments more manageable.

In each of these cases, isolation not only helps in administering specific treatments but also aids in closely monitoring the fish’s progress and adjusting care as needed.

How Do I Consult an Aquarium Vet?

Consulting an aquarium vet involves preparation and clear communication about your fish’s health.

It’s important to gather relevant information and present it in a way that allows for an accurate diagnosis.

  • Detailed Symptoms: Note all symptoms observed, such as changes in eating habits, appearance, and behavior, to give the vet a clear picture of the fish’s condition.
  • Tank Conditions: Provide information on tank size, water parameters (temperature, pH, ammonia levels), and any recent changes to the environment.
  • Medical History: Share any past illnesses and treatments your betta has had, including medications used and responses to those treatments.
  • Photographic Evidence: Take clear photos or videos of the sick fish and any visible symptoms, as these can be crucial for remote consultations.
  • Sample Collection: If possible, bring a sample of your tank water to the consultation for testing, as water quality plays a significant role in fish health.


Ensuring optimal water quality is crucial in preventing many common diseases in betta fish, which is certainly a relief.

If you do observe any signs of illness in your betta, the initial step should be to quarantine the affected fish.

This helps in preventing the spread of the disease to other fish. Also, think about adjusting or changing the water conditions.

Following that, I strongly suggest consulting with an aquatic veterinarian. They can provide specialized advice and further recommendations for your betta’s health.