Common Betta Fish Illnesses and Diseases: A Comprehensive Guide

There are few things as heartrending as discovering that your beloved betta is ill. These hardy little fish don’t get sick often, which can make it even more frightening when they do.

With good care, you can generally lead your fish through the valley of death and back to health. The key is knowing about and understanding the common betta fish diseases.

In this article, we’ll take a closer look at some of the common ailments, their causes and symptoms, and how to deal with them.

Betta Diseases and Treatments in a Nutshell

While we’ll be covering the diseases and treatments in detail later on, we know you’re anxious to find answers so here are some handy tables for your reference:

Disease Symptoms and Causes

Fin and Tail RotFrayed and discolored fins and tail,  tissue dying and breaking offBacterial infection,  poor water quality,  poor nutrition
ColumnarisOpen sores,  ulcers,  white or gray cottony growths on skin and finsBacterial infection,  poor water quality
HemorrhagicRed or purple streaks on the body and fins,  difficulty breathing,  lethargyBacterial infection,  stress
DropsyDistended belly,  scales that stick out from the bodyBacterial infection,  poor water quality, poor nutrition
Pop EyeCloudy or bulging eyesPoor water quality,  injury,  underlying health issues
EyecloudCloudy eyesPoor water quality,  injury,  underlying health issues
Mouth FungusWhite or gray cottony growths on the mouthFungal infection,  poor water quality
FurunculosisOpen sores,  ulcers,  abscessesBacterial infection,  poor water quality
Fish FungusWhite or gray cottony growths on skin, fins, and mouthFungal infection,  poor water quality
VelvetGold or copper-colored dust on skin and finsParasitic infection,  poor water quality
IchWhite spots on skin and fins,   scratching against objectsParasitic infection,  poor water quality
Anchor Worms
Irritation,  open wounds
Parasitic infection
Hole in the HeadLesions or holes in the head,  weight loss,  loss of appetiteBacterial or parasitic infection,  poor nutrition
Swim Bladder DisorderDifficulty swimming,  floating or sinkingPoor nutrition,  constipation,  underlying health issues
Betta TumorsTumors or bumps on the bodyUnknown


 SurgeryAnti- bioticsReduce StressWater ChangesImproved  NutritionAnti- fungal MedicineAnti- Parasitic medicineAddress Underlying Causes
Fin and Tail Rot X XX   
Columnaris X X    
Hemorrhagic XXX    
Dropsy X XX   
Pop Eye   X   X
Eyecloud   X   X
Mouth Fungus   X X  
Furunculosis X X    
Fish Fungus   X X  
Velvet   X    
Ich   X  X 
Anchor Worms   X  X 
Hole in the Head X XX X 
Swim Bladder Disorder    X  X
Betta TumorsX       

Common Betta Fish Illnesses

As we mentioned above, bettas are pretty hardy little fish. In the wild, they often live in stagnant ponds and rice paddies, so they have a high disease resistance. 

However, there are certain ailments to which they’re more susceptible. Below, we’ll take a closer look at some of them, and what they are.

Fin rot 

Fin rot is one of the most common betta fish diseases. It’s generally the result of a bacterial or fungal infection taking root in any small scrape or wound. 

Fin Rot by Dizzy Respect CC BY-SA 4.0


Popeye is another type of infection that leads to one or both of your betta fish’s eyes bulging out of their skull. It’s generally a sign of some underlying health issues, or the result of an infected injury (especially around the fish’s face).


Ich, or white spot, is the bane of any aquarist’s existence. It’s an incredibly common parasite that dwells in gravel, and many fish carry it on them without it ever manifesting.

white spot between the eyes

However, if the fish gets ill from something else or suffers unusual amounts of stress, it can manifest at any time. 


Less common than the other diseases listed here, Velvet is a parasitic infection resulting from poor water conditions.



Unfortunately, Dropsy is a relatively common disorder in aquarium fish. It’s a type of bacterial infection caused by inadequate water conditions.

Courtesy of Shayann Ch.


Cottonmouth is a type of mouth fungus that looks like the fish is carrying around a small ball of white or gray cotton wool. This fungal infection can be the result of injuries to the mouth or water that isn’t clean enough.

Swim Bladder Disorders

All bony fish rely on their swim bladders, an organ filled with atmospheric oxygen, to keep them afloat. Cartilaginous fish like sharks and stingrays lack a swim bladder, which is why they have to stay in constant motion.

In certain cases, when fish collide with obstacles or simply bump their swim bladders, this organ can form a leak or rupture. Swim bladder disorders and ruptures are potentially lethal, and generally will be.  

Symptoms and Diagnosis

Now let’s take a closer look at their symptoms, and how to diagnose the problem.

Below, we’ll mention some of the common symptoms, and tell you which diseases can lead to them. You can scroll to the appropriate symptom, and see if any of the mentioned diseases match what you’re seeing.

1. The Fish has Fluffy White Growths on Its Fins, Tail, or Mouth

Several fungal infections and diseases manifest as fluffy white growth on parts of the fish.

If you see a cotton-wool-like growth on your betta fish’s mouth, then cottonmouth is the most likely culprit.

If the growths form around an existing wound, then it can be the result of any of the common fungal infections or even less common fungi.

If the tails and fins are the main affected areas, then you’re probably dealing with normal fish fungus, which is relatively harmless if treated immediately.

2. The Fish Has Small White Spots or Larger White Patches on Body Parts

Several common Betta ailments manifest as small or large white spots on the body, tail, and fins.

If the spots are relatively small, and plentiful, then Ich or White Spot is the most likely culprit. If the patches are quite large, then Columnaris is a likely problem.

3. The Fish’s Tail and Fins Look Ragged Like Parts are Missing

If your fish displays a tail that looks ragged, lacks its usual luster, or just doesn’t seem healthy, then your betta might have tail or fin rot. It’s a fungal infection thatff systemically devours parts of the tail.

If the tail seems to have white growths on the missing part, then the fish may:

  • Be the victim of bullying by its tankmates
  • Have a secondary fungal infection in addition to the fin rot

4. The Fish Struggles to Stay Upright or Wobbles While Swimming

If you notice that your fish tends to lean to one side, turn upside down, or has problems with staying upright, then it probably has a swim bladder disorder.

This is usually the result of an argument with other fish or the fish swimming into something.

5. The Fish has Open Sores or Ulcers

Several of the more severe betta fish diseases result in sores or ulcers.

If the sores are mainly on the skin and fins, then columnaris is a likely culprit. In these cases, the sores will often have white, cottony growths around them.

If the sores occur mostly on the head and take the form of eroded “pits”, then hole-in-the-head disease is the probable cause. 

Furunculosis is another disease that may lead to legions, sores, and abscesses throughout your betta fish’s body.

6. The Fish Has No, or Reduced, Appetite

Any sort of intestinal problem can lead to reduced appetite. The problem may be as simple as constipation. 

However, loss of appetite may also be a symptom of hole-in-the-head disease or bacterial infections.

7. The Fish’s Eyes are Bulging or Clouded

If your fish’s eyes look cloudy but aren’t bulging in any way, then they’re likely suffering from eyecloud, which is a simple bacterial infection.

If its eyes are both bulging and cloudy, then you’re probably dealing with popeye.

8. The Fish Has Discolored Skin

If your fish has red or purple discoloration, that it didn’t have before, then you’re likely dealing with something hemorrhagic.

If your fish has a dusted appearance, looking like they’ve been sprinkled with gold or copper-colored glitter, then you’re likely dealing with velvet.

Betta Disease and Illness Prevention

Most doctors agree that prevention is better than cure, and the same thing is true with your pet betta fish.

While fish may sometimes get sick without any apparent cause, diseases and illnesses are usually triggered by one of a few main causes. These include:

  • Stress
  • Inadequate water conditions
  • Wounds and injuries
  • Old age
  • Sudden changes in water parameters, temperatures, or other conditions

If you want to keep your fish as healthy as you can, for as long as possible, try to stick to the following guidelines:

  • Try not to change any tank conditions rapidly. If you feel that the water pH, hardness, temperature, or another factor needs changing, make the change systematically over a week or two, to avoid sending the fish into shock.
  • Avoid stressing the fish in any way. A stressed-out fish is much more susceptible to parasites, diseases, and infections. Here’s how:
    • If you notice that one of your fish has nippish tendencies, don’t keep it with your betta fish.
    • Avoid keeping male bettas with significantly larger fish, or fish with the same coloration, as this can be stressful to these fish.
  • Keep the tank water clean by doing regular water changes, siphoning the gravel, and not allowing uneaten food or other debris to decompose in the aquarium.
  • Wounds and injuries usually occur either as the result of your betta’s interaction with tank elements or other fish in the aquarium. If you notice that your betta fish are forming wounds from bumping into certain decor items, or from interacting with tankmates, move the offending decoration or fish to a different aquarium.

Treatment of Betta Diseases

Most common betta ailments can be divided into one of several groups. They may be:

  • Fungal infections – Fish fungus, Mouth fungus
  • Bacterial infections – Popeye, Eyecloud, Hole in the head disease, Furunculosis, Hemorrhagic, Dropsy, fin and tail rot, 
  • Parasitic infections – Ich/white spot, Anchor worms, Velvet, Columnaris

The two major exceptions to this grouping would be swim bladder disorders and betta tumors. Let’s take a look at how to treat them first:

Swim Bladder Disorders

Swim bladder disorders may be the result of constipation, inadequate nutrition, or physical damage to the swim bladder. There aren’t always many things you can do to help fish with this condition, but you have options. 

The most important things to do are deal with the constipation (if present) and ensure that the fish is getting adequate nutrition.

If you’re dealing with a ruptured swim bladder, there’s only one option that is occasionally successful for experienced fishkeepers. You can place your fish in the material “fry savers” or “maternity boxes/cages” that you buy at the pet store.

The idea is to keep the fish in a stable position and prevent it from trying to swim around too much. So place the mesh cage so that it’s relatively shallow, just deep enough to entirely cover your betta. Then place an air stone or aerator underneath it at a very low setting. 

You want to provide the betta with additional oxygen without making the water too turbulent. While ruptured swim bladders may heal, you shouldn’t get your hopes up too high. If successful, the fish will heal slowly over a few days or weeks, and you should see them regaining their normal balance and mobility.

I have used this method with great success for some cory cats and labyrinth fish that ruptured their swim bladders while arguing with their tankmates.

Betta Tumors

While tumors may sound catastrophically serious, they’re rarely anything to worry about in your fish. Taking the form of conical growths or large bumps, they’re a bit of an eyesore but generally harmless.

If you’re worried that the tumors may be affecting your fish’s quality of life, then you can consider having them surgically removed. However, bear in mind that it’s a fairly expensive procedure for a fish that rarely has a lifespan of more than two years.

If the tumors turn out to be harmful, then your vet may suggest euthanasia. 

Parasitic Infestations or Infections

Parasites often take root when a fish is stressed through poor water quality or some other underlying cause. Treating them is fairly simple, but also a hit-and-miss process.

For ich, or white spot, you get specific medications, while the others can be treated using a general, copper-based antiparasitic.

Unfortunately, the medication that kills your fish’s parasites is also mildly toxic to your fish. The parasites themselves are also mildly toxic when they start dying in your fish’s body.

The choices are less than stellar, and come down to:

  • Certain death, without treating the parasites
  • Potential death, with treating the parasites

When using anti-parasitic medication, be sure to follow the directions on the bottle carefully, for best results. 

Bacterial Infections

Most bacterial infections are relatively easy to treat with a dose of aquarium antibiotics. You should also do more regular water changes for a while after the antibiotic treatment. 

Antibiotics for aquariums often require that you remove the charcoal from the filter, and not do any water changes, for a few days to a week. This is because charcoal uses carbons to remove chemicals, including antibiotics. Water changes, naturally, also serve to remove or dilute the antibiotics.

While off-the-shelf antibiotics are often effective, you’ll get the best results if you get a prescription from the vet for your particular bacterial infection.

Fungal Infections

Fungal infections are some of the easiest things to treat. You can buy medication off-the-shelf, and it’s generally a lot easier to use than antibiotics or antiparasitic medication.

Simply follow the directions on the bottle, and do more regular water changes for a while to help clean the fungus from the water.


With fish, as with humans, there’s always the chance of a new or uncommon infection. We’ve covered the most commonly seen betta illnesses above, and given you the tools you need to deal with them.

However, they’re susceptible to any range of parasites and illnesses beyond this. If your betta fish is ill, and you don’t know what’s wrong, we’d recommend taking it to a vet.

Please rember to quarantine any fish that does not seem healthy to protect the other fish in the tank.

Have you had any great experiences with betta fish recovering from ailments? If so, we’d love to hear from you. Feel free to contact us, and let us know. 

About the author

Hi, I’m Johanan! I love animals of all shapes and sizes, but especially fish. I’ve gone from working at a pet store as a teenager to keeping and breeding Bettas and other fish at home. My passion for fish is endless!

You can find my articles here.

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