23 Common Betta Diseases: Signs, Treatment, And Prevention

Poor tank maintenance is the number one cause of betta diseases.

Improper temperatures, poor water quality, and bacteria buildup lead to sick betta fish.

Learning to spot the common symptoms of diseases is crucial for your betta’s health.

And quick disease treatment increases your betta’s chance of recovery.

#1 Fin and Tail Rot

betta fish fin and tail rot

Bacteria or fungi cause fin and tail rot. Injuries to your betta’s fins or tail increase the risk of this disease.

Signs of this common disease include ragged fins with red, black, or bloody edges.

If fin and tail rot is not promptly treated, it spreads to the body.

The treatment for fin and tail rot includes antibiotic medications, such as:

  • Trimethoprim
  • Erythromycin
  • Sulfadimidine

With prompt treatment, this disease is usually not fatal.

Once your betta recovers, its fins, and tail will grow back. However, the color and length of the fins and tail may not be the same as before.

Prevent fin and tail rot by keeping the betta tank clean with regular water changes and algae removal.

Avoid overcrowding or adding fish known to nip fins if your betta is in a community tank.

#2 Columnaris

betta fish columnaris

Columnaris is a bacterial disease caused by poor water conditions. Bettas with open wounds are more susceptible to this disease.

Signs of Columnaris include:

  • Skin ulcers or lesions
  • Frayed fins
  • White spots on the mouth
  • Discolored gills
  • Cotton-like growth on the scales, fins, and mouth

Columnaris is usually treated with:

  • Oxytetracycline
  • Antibiotics with Sulfa 4 TMP
  • TMP Sulfa
  • Triple Sulfa

If Columnaris is not treated within 72 hours, your betta may die.

Columnaris is prevented by treating fungal infections and open wounds on your betta as soon as you see them.

Keep your betta tank clean with regular water changes and adjust the pH if you have hard water.

#3 Hemorrhagic

betta fish hemorrhagic

Hemorrhagic, also known as redmouth, causes severe bleeding in the betta’s mouth and eyes.

You may also see red streaks or open sores on the fins and body.

Redmouth is caused by the bacteria Yersinia ruckeri.

This disease is highly contagious. Remove the fish immediately if your betta is in a communal tank and you notice signs of redmouth.

Treatment for redmouth involves disinfecting the entire betta tank and giving your fish an antibiotic like ampicillin.

The fatality rate is low if hemorrhagic is treated in the early stages.

Hemorrhagic is prevented by keeping the tank clean to prevent the Yersinia ruckeri bacteria from forming.

Remove algae and do a 30% water change in your tank once a week. Remember to treat tap water with a dechlorinator, and maintain proper temperatures and water parameters.

#4 Dropsy

betta fish dropsy

Dropsy is an illness affecting the kidneys. As dropsy progresses, fluid builds up in the kidneys and liver, causing swelling.

Stressed or sick bettas are more prone to dropsy.

Early signs of dropsy in your betta include:

A betta with the later stages of dropsy has a swollen abdomen. The fish also has sunken eyes and protruding scales.

Dropsy is typically caused by the following:

  • Viral disease
  • Parasites
  • Bacteria
  • Poor nutrition

There is no cure for dropsy, but medications like amoxicillin, methylene blue, or aquarium salts will help in the early stages.

Unfortunately, by the time your betta’s abdomen is swollen, it is too late, and your betta will die.

Prevent dropsy by regularly cleaning your tank and feeding your betta high-quality food. Treat sick bettas at the first signs of illness and avoid putting your fish in stressful situations.

#5 Pop Eye

betta fish pop eye

Pop eye causes swollen eyes in bettas. The swelling may affect one or both eyes.

A bacterial infection is the leading cause of pop eye. However, sometimes pop eye is a symptom of other diseases, such as cancer or tuberculosis.

Early signs of popeye include a change in eye color or a white ring around the eyes.

Pop eye is treated with a tetracycline antibiotic. The tank must also be disinfected to kill the bacteria.

Prevent pop eye by maintaining water parameters and keeping the betta tank clean.

You may also avoid popeye by not feeding your betta live food.

#6 Cloudy Eye

betta fish cloudy eyes

Eye cloud, also known as cloudy cornea, causes a white film on the betta’s eyes.

In severe cases of eye cloud, the betta’s eyes appear opaque.

Other signs of cloudy eyes include a mucus buildup on the betta’s body and difficulty swimming.

Your betta’s vision will be impaired, and it may have difficulty seeing food.

Eye cloud is not fatal but leaves your betta vulnerable to other illnesses.

You must remove your betta to a quarantine tank to treat eye cloud. Then, add one tablespoon of aquarium salt for every five gallons of water.

Once the condition improves, you may move your betta back into its home tank.

Eye cloud is easily prevented by maintaining a clean tank with proper water parameters. Sanitize the water filter every month and feed your betta a protein-rich diet.

#7 Mouth Fungus

betta fish mouth fungus

Mouth fungus is a bacterial disease causing white lines around the mouth of the betta.

You may see white clumps resembling cotton on the mouth as well.

This disease is similar to columnaris, except it occurs primarily in the mouth.

If mouth fungus is not treated early, the infected betta will die.

Medications such as amoxicillin and methylene blue successfully treat mouth fungus.

Maintaining water parameters and keeping the tank clean prevents mouth fungus.

#8 Furunculosis

betta fish Furunculosis

Common signs of furunculosis are open sores and ulcers on the betta’s body, fins, and tail.

Furunculosis is caused by the bacteria Pseudomonas and Aeromonas. These bacteria thrive in poorly-maintained tanks.

If your betta is stressed or suffering from another illness, it is more likely to be affected by furunculosis.

Furunculosis is deadly for bettas without prompt treatment.

Signs of furunculosis in bettas include:

  • Red patches on the body
  • Red, pus-filled sores
  • Lethargy
  • Loss of appetite

Isolate an infected betta in a separate tank to treat it with antibiotics like erythromycin or tetracycline. Clean and disinfect the main tank with iodine and salt to remove the bacteria.

Furunculosis is prevented by maintaining proper water parameters and temperatures in the tank.

#9 Fish Fungus

betta fish fungus

Fungal diseases usually stem from previous skin infections.

Common signs of fish fungus include:

  • Cottony growths
  • White fuzz
  • Slime
  • White lumps and bumps on the skin
  • Lack of appetite
  • Lethargy

Without quick treatment, fish fungus is fatal to bettas.

Spot-treat your betta with a 50% mercurochrome solution on the affected areas.

Other treatments for fish fungus are methylene blue, Fungus Clear, and Bettafix Remedy.

Fungal diseases are prevented by promptly treating infections and injuries. Keeping the tank clean and performing regular water changes is also vital.

#10 Velvet

betta fish velvet

Velvet is a highly-contagious parasitic disease.

Signs of velvet in bettas are:

  • Rust-colored skin
  • Scaly head, gills, and abdomen
  • Black spots
  • Color loss

Long-term stress, poor water conditions, and cold water temperatures cause velvet.

You must remove your betta to a separate tank to treat the home tank first.

Treat velvet by turning the tank lights off and ensuring the water temperature in the tank is at least 85° degrees Fahrenheit (29° C). The parasites causing velvet will not survive these conditions.

Once this has been done, thoroughly clean the tank, including the filter, plants, and decorations.

Treat your betta with a malachite green remedy to cure the velvet. Unfortunately, it may take up to two weeks to completely eradicate velvet.

If your betta is in a community tank, you must treat all the fish in the tank, even if they do not show velvet symptoms.

Velvet is prevented by maintaining healthy water parameters and ensuring the tank temperature is at least 78° degrees Fahrenheit (26° C).

You must also avoid causing stress to your betta.

#11 Ich

betta fish ich

Ich has a couple of names, including ick and white spot.

This parasitic disease causes white dots or rings all over the betta’s body. This includes the belly, gills, fins, and tail.

Your betta will rub its body against the sides of the tank and decorations in an attempt to remove the parasites.

Ich is often introduced into the tank by frozen live food. Be careful where you source your betta’s food to ensure it does not contain ich or other parasites.

Treat the tank with a commercial ich medication containing copper sulfate, formalin, or malachite green.

Thoroughly clean the tank and its contents and perform a water change.

Prevent ich by maintaining constant water parameters and tank temperatures.

Regularly test the water in your betta tank for ammonia, nitrites, pH, and dissolved solids.

#12 Anchor Worms

betta fish anchor worms

Anchor worms are a rare form of parasite.

Despite their name, anchor worms are not worms. Instead, they are a type of crustacean called Lernea.

Anchor worms infect your betta by attaching to the skin and burrowing into the body.

These parasites are visible on your betta and grow up to 1/8th of an inch.

Other signs your betta has anchor worms include:

  • Rubbing on the tank/decorations
  • Ulcers/sores
  • Breathing problems

A commercial parasite remedy or an antibiotic like methylene blue treats anchor worms in bettas.

If the anchor worms are not treated early enough, your betta could die.

Prevent anchor worms by promptly treating newly-infected bettas and maintaining a clean tank.

#13 Hole in the Head

betta fish hole in head

Hole in the head is as terrible as it sounds, and the cause is unknown.

Look for signs of hole in the head, such as:

  • White, stringy feces
  • Loss of color
  • Small holes in the head or body

The holes will look like a pinhole or white fuzz.

A hole in the head is treated with medications like dimetridazole or metronidazole.

This disease is fatal in bettas, often killing them within five days of infection.

To prevent hole in the head, feed your betta a nutritious diet and ensure your water parameters are correct and consistent.

#14 Swim Bladder Disorder

betta fish swim bladder disorder

Swim bladder disease is common in bettas, and it causes them to float near the water’s surface.

The affected betta may swim sideways or upside-down and stay near the bottom of the tank. You might also see your betta doing the vertical death hang from this illness.

Swim bladder disorder may also cause a bloated belly and loss of appetite.

Common causes of swim bladder disorder in bettas include:

  • Stomach issues/constipation
  • Overfeeding
  • Parasites/bacterial infections
  • Birth defects
  • Egg-binding
  • Physical injury
  • Shock
  • Low water temperature

Fortunately, swim bladder disease is rarely fatal, and the betta will have a speedy recovery.

Treatment for swim bladder disorder involves not feeding your fish for at least three days and raising the water temperature in the tank.

Fasting does not harm your betta and allows the fish to digest its food completely.

Warmer tank temperatures also aid in digestion. Ensure tank temperatures are between 78-80° degrees Fahrenheit (27° C).

Prevent swim bladder disease by not overfeeding your fish and maintaining correct water parameters. Do not allow temperatures in the tank to drop too low.

#15 Betta Tumors

betta fish tumors

Betta tumors appear as lumps or small cysts under the skin.

These tumors are usually cancerous and mainly affect the following:

  • Reproductive organs
  • Gills
  • Tail
  • Abdomen

Betta tumors are usually the result of viral infections or genetic mutations.

Tumors require veterinary care since surgery is needed to remove them.

Malignant tumors are challenging to cure, but benign tumors and cysts are usually removed easily.

Many bettas still live full lives with tumors. Therefore, treatment usually is unnecessary if your betta is acting normally.

Surgery is often quite expensive, and euthanasia is the best option if your betta is suffering.

Betta tumors may be prevented by:

  • Feeding a nutritious diet
  • Keeping the tank clean
  • Promptly treating infections
  • Keeping carcinogenic substances away from the tank

Some betta species are more prone to tumors than others, and there is no way to prevent them from appearing.

#16 Tuberculosis

betta fish tuberculosis

Tuberculosis is a very rare disease in betta fish. However, it quickly progresses, and you may not know your fish has tuberculosis until it suddenly dies.

Tuberculosis in bettas is caused by a mycobacterium found in some aquariums. Bettas with lowered immune systems are likelier to contract tuberculosis.

Symptoms of tuberculosis include:

  • Weight loss
  • Deformed spine
  • Open sores
  • Fin and tail rot
  • Loss of appetite
  • Lethargy
  • Protruding eyes/discoloration

Use caution when handling your betta if you suspect it has tuberculosis. The disease is highly contagious and may be passed from fish to humans.

Unfortunately, there is no cure for tuberculosis. By the time your betta shows symptoms, the organs have already started failing, and your betta will die.

Prevent tuberculosis by feeding your betta a healthy diet, avoiding stressful situations for your fish, and keeping the tank clean.

#17 Constipation

betta fish constipated

Bettas suffering from constipation are unable to empty their bowels.

The feces become hardened in a betta’s stomach when fed a poor diet.

Common symptoms of constipation are:

To treat constipation, start by fasting your betta for around three days.

If your betta still has no bowel movement, feed it high-fiber foods like peas and daphnia.

In severe cases of constipation, you may treat your betta with Epsom salt in a separate container.

Constipation may be avoided by feeding your betta a nutritious diet, not overfeeding, and keeping the tank clean.

#18 Fish Lice

betta fish lice

Fish lice are a parasite commonly found in freshwater tanks. Infected fish usually bring in the lice.

These parasites attach to your betta’s body and feed on its blood and other body fluids.

A common sign of fish lice is red sores on the betta’s body. You may also see the parasites on your betta’s skin.

Other signs of fish lice on your betta are:

  • Rubbing against the tank/decorations
  • Lethargy
  • Abnormal swimming

To treat fish lice, you must place your betta in a quarantine tank and treat it with aquarium salt.

You must thoroughly disinfect the home tank and all of its contents to ensure the lice and their eggs are removed.

Prevent fish lice by quarantining any new plants or fish you plan to put in your betta tank for at least two weeks.

#19 Gill Parasites

betta fish gill parasites

Gill parasites, also known as gill flukes, attack your betta’s gills. Unfortunately, these parasites are tiny, so it isn’t easy to recognize them.

Dirty water creates a breeding ground for gill parasites. They are also brought into the tank by other fish or plants.

A betta infested with gill parasites will struggle to breathe when it comes to the surface. The gills may also be covered in a slimy film or open sores.

Your betta fish will also rub against the sides of the tank or decorations in an attempt to remove the gill parasites.

Treatment for gill parasites involves a commercial anti-fluke medication or aquarium salts.

#20 Intestinal Parasites

betta fish intestinal parasites

Intestinal parasites feed on whatever your betta eats, depriving your fish of nutrition.

These parasites are usually found in certain betta foods, such as worms. Intestinal parasites are not as common as external parasites in bettas.

The main sign of intestinal parasites in your betta is weight loss, even if the fish is eating normally.

Your betta may also become lethargic as it loses energy from a lack of nutrition.

Treat intestinal parasites in bettas with a commercial antibiotic remedy. It would be best if you also cleaned the entire tank, including the decorations.

You may add aquarium salt to the new water to ensure the parasites are completely gone.

The best way to prevent intestinal parasites is to keep your betta tank clean and buy live or frozen betta foods from a reputable source.

#21 Poisoning

betta fish ammonia poisoning

Poisoning in bettas is directly caused by unclean water.

High levels of ammonia, nitrate, and nitrite are toxic to your betta.

A betta suffering from poisoning will stay near the top of the tank and frequently gasp for clean air.

If you notice this behavior in your betta, you must test your tank’s ammonia, nitrate, and nitrite levels.

Remove your betta to a quarantine tank and change the water in the main aquarium.

Remember to add a dechlorinator if you use tap water. Keep testing the water until the proper parameters are met.

#22 Slime Disease

betta fish slime disease

Slime disease is an illness caused by parasites. This disease weakens the betta’s immune system, making them prone to infections and other conditions.

The parasites causing slime disease are Costia, Cyclochaeta, and Chilodonella.

Symptoms of slime disease include:

  • Frayed fins
  • Grey/white mucus coating
  • Loss of appetite
  • Lethargy
  • Cloudy eyes

Treat slime disease with malachite green and a small amount of aquarium salt. Change the water in the tank every day for up to one week.

Prevent slime disease by maintaining correct water parameters and cleaning your betta tank regularly.

#23 Bacterial Septicemia or Red Streaks

betta fish septicemia

Bacterial septicemia is rare in betta fish. It is caused by the Pseudomonas or Streptococcus bacteria.

This disease is fatal in bettas without prompt treatment.

Symptoms of bacterial septicemia include:

  • Red streaks on the body and fins
  • Bloating
  • Gasping for air
  • Ulcers
  • Lethargy
  • Loss of appetite

Bacterial septicemia in betta fish requires veterinary care. The betta is placed in a quarantine tank and treated with an antibiotic until the disease is cured.

Keep Your Betta Healthy

Recognizing betta diseases is vital for ensuring your fish receives prompt treatment.

The sooner you treat the disease, the easier it is for your betta to recover.

Maintaining a healthy living environment and feeding your betta a nutritious diet prevents the most common fish diseases.

Frequently test your water to ensure it meets the correct parameters. Perform partial water changes more often if you have a tank smaller than 10 gallons.

With extra care, you will keep your betta healthy and happy.

How useful was this post?

Click on a star to rate it!

As you found this post useful...

Follow us on social media!

We are sorry that this post was not useful for you!

Let us improve this post!

Tell us how we can improve this post?


Toni Tedescucci is a freelance writer who loves all animals, especially betta fish. When she isn’t busy writing for Betta Fish Bay, she’s spending time with her family or getting cozy with her cats and a good book.

Follow Us on Facebook!

Get betta fish fun facts right on your Facebook feed and see when we share new content by following our page on Facebook.

blue betta fish

Advertiser Disclosure

We are reader-supported and may earn an affiliate commission when you buy through links on our website. To be 100% clear, you should assume that we will earn a commission on any product you purchase after clicking on links or images on this website.

Our affiliate partners include but are not limited to Amazon.com.

In addition, we generate revenue through advertisements within the body of the articles you read on our site.

Although we only recommend products that we feel are of the best quality (which we may or may not have personal experience with) and represent value for money, you should be aware that our opinions can differ.

A product we like and recommend may not be suitable for your unique goals. So always be sure to do your due diligence on any product before you purchase it.