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10 Betta Fish Diseases: Symptoms, Treatments & Prevention

A sick betta is always cause for concern, but the real issue comes when we don’t know what’s wrong. The entire ordeal is taxing for the fish and fishkeeper, as they hope for some relief for the fish. However, if you don’t know the common betta fish diseases, it can be tricky to find what’s ailing your beloved friend.

As a betta owner, your primary goal is to keep your pets alive, happy, strong, and healthy. So, an essential part of your fish first aid kit should be your knowledge of the different betta fish diseases. Luckily, we’ve curated a list of the most common illnesses that plague our betta.

Read on as we explore our comprehensive list of betta fish diseases, how to spot them, and how to care for a sick betta 

The FishKeeper’s List of Common Betta Fish Diseases

In the world of betta fish diseases, some are far more common than others. This can be a good thing because common diseases are often studied and documented extensively. This means they’ll be easier to diagnose.

Here is a list of 10 common betta fish diseases, along with their alert signs and the first line of action:

Fin Rot

Betta fish fin rot can be a fishkeeper’s nightmare because he or she watches it gnaw away at their beloved betta’s extremities very quickly. In literal terms, it’s caused by a bacterial infection that affects the fins, tail, and mouth over time.

When a betta is sick with fin rot, their immune system is greatly weakened and now susceptible to other possible diseases. If neglected, the infection will claim the entire body of the sick fish and kill it. So, you must act quickly to boost your betta’s chance. 

What You’ll Notice:

  • Rotting and incomplete fins 
  • Lethargy

What You’ll Do:

  • Since fin rot is often caused by poor water conditions, start by performing a water change 
  • Next start the sick betta fish on antibacterial and antifungal medication to kill off what thrives in the diseases.

Swim Bladder Disease

Swim bladder disease does exactly what you’d expect: damage the swim bladder in your sick betta. It leaves your friends swimming in a tilted and lopsided direction, so the symptoms are pretty hard to mix up. Swim bladder disease doesn’t just make your fish swim funny, it also hinders them from keeping afloat.

The main cause of swim bladder disease is poor water quality, so the first thing we want to do is change the aquarium water. After changing the water, separate the ailing fish and quarantine him away from his roommates.

What You’ll Notice:

  • Your betta is swimming with erratic and struggled movements 
  • Floating vertically or even upside down
  • Swollen abdomen
  • Loss of appetite 

What You’ll Do:

  • Create a special tank unit for housing sick fish, called a quarantine tank. This will help you monitor your sick fish closely, and prevent healthy fish from contracting infectious diseases.
  • Add in epsom salt to the quarantine tank to reduce the pressure on your betta’s abdomen. 
  • Don’t feed the betta for 48-72 hours to clear their stomach
  • Keep a keen eye on the water parameters and manage the quality
  • You can also adjust their diet to reduce bloating by feeding appropriate portions of proteinous feed


Ich is a betta fish disease caused by the parasite called Ichthyophthirius multifiliis. Like a true ectoparasite, it looks for a host and appears as white patches on the host body. It can be uncomfortable to watch a sick fish with ich, but it’s probably even worse when they lie on your skin.

What You’ll Notice:

  • The ich parasite will lay small cotton ball-like patches on your betta’s skin to deposit its immature parasites. These small but new white patches should be a cause for concern when dealing with a sick fish
  • Fish suffering ich are often…itchy. You’ll see them rubbing their bodies on the aquarium walls to release the ich parasite

What You’ll Do:

  • After identifying ich, the most effective step is to begin an immediate ich treatment. The process will involve adding some treatment to the water and increasing to 85 degrees fahrenheit, causing the ich cysts to rupture and die. 
dropsy disease


When it comes to betta fish diseases, dropsy sits at the more lethal end of the spectrum. It’s triggered by a bacterial infection that causes renal failure in the sick fish. Like other less serious diseases, poor water quality is often to blame. Sadly, there isn’t much you can do for a betta fish sick with dropsy because the survival rate is low.

What You’ll Notice:

  • Severely swollen and bulging eyes
  • Pinecone scale, which is when your betta’s scales protrude outward instead of laying flat on their body 
  • Swollen abdomen 
  • Curved spine

What You’ll Do:

  • Immediately, when you notice signs of dropsy, isolate the affected fish in a quarantine tank.
  • If you have some aquarium salt (epsom salt) in your betta first aid kit, administer one teaspoon per gallon. The salt should help draw fluid from inside your betta and abate the swelling
  • Administer edible anti-fungal pellets to help your fish fight the infection 

Cotton Wool Disease

Cotton wool disease is a common betta fish disease, scientifically named Flexibacter columnaris. It has different names among fish enthusiasts, including cotton mouth disease, saddleback disease, and guppy disease. 

Unlike fungal infections, the culprit of cotton wool disease is a bacterium called Flavobacterium Columnare. This bacterium thrives when there is poor water quality, and low oxygen.

What You’ll See:

  • If affected with cotton wool disease, your vibrant betta will lose its colors and become a much duller shell of its previous self. 
  • Your betta’s gills will start experiencing necrosis, where the gills will dull and begin to die. Here, the betta typically has trouble breathing. 
  • Another tell-tale sign is fluffy cotton-like growths around your betta’s fins, mouth, and body. 
  • You may notice ulcers all over your betta’s flesh.

What You’ll Do:

  • Start by isolating the ill fish away from healthy fish in a quarantine tank, and over the next few days, slowly reduce the aquarium’s temperature to 75 and 77 degrees fahrenheit.
  • Begin drug therapy with a suitable antibacterial medication, but not before removing any chemical filtration media from the tank.
  • As you treat the betta, use water conditioners and conduct 25% water changes every few days. This bit helps eliminate the Flavobacterium Columnare bacterium from the aquarium.

Vertical Death Hang

Vertical death hang often presents as a symptom of swim bladder disease. Your betta suddenly floats in a vertical position without moving. While it’s commonly associated with swim bladder disease, poor water quality can also cause the lethal vertical death hang.

What You’ll See:

  • Your fish will float in a vertical pose, with their mouth facing the surface of the tank.

What You’ll Do:

  • Since poor aquarium quality is the primary cause of vertical death hang, monitor water conditions, making sure to change 25% of the tank water every few days.
  • If you think your betta may also be constipated, give them high-quality daphnia to help them pass any stool.


Popeye is a betta disease triggered by a plethora of causes. Some of the common causes are fungus, bacteria, parasites, and even a physical injury. But here’s the funny bit, popeye can affect other animals and even humans.

The brainy name for popeye is exophtalmia, which indicates a buildup of pressure causing the eye to protrude. But if you don’t act fast, your betta fish can die.

What You’ll Notice:

  • One or both of the eyes bulging 
  • Eye discoloration, as it turns cloudy or milky 
  • A white ring around the eye

What You’ll Do:

  • If your betta’s popeye is rooted in disease or parasites, then start by whipping out the quarantine tank. Then, you should immediately change the original tank water to get rid of pathogens in the aquarium 
  • Use aquarium salt to abate the pressure and administer over-the-counter antibiotics. Remember to conduct a 100 percent water change every three days 
  • If your betta’s popeye is caused by physical injury, then its chance of survival is much higher. Simply prepare him a bath with aquarium salt, using 1 teaspoon per gallon


Tumors in betta fish often indicate deeper underlying issues. Whatever the cause, these tumors mess with the betta’s buoyancy and make them have a hard time swimming. So, a visible tumor on your betta is always a cause for concern.

Some common causes of tumors in a sick betta are poor water conditions, bad diets, and infections introduced by new tankmates. 

What You’ll See:

  • A bump on the surface of your betta’s body
  • Inability to keep afloat or swim properly 
  • Lethargy

What You’ll Do:

  • While treating your betta’s tumor, it s important to isolate them from healthy fish.
  • Now, check and ensure that the water parameters are ideal.
  • If you’re unsure of the tumor’s cause, then you should seek prompt advice from a veterinarian. Administering medication without a diagnosis can make the situation worse.


Velvet is a parasitic infection caused by the Oödinium parasite. It affects freshwater and saltwater fishes, and it is very common with betta fish. If your betta is sick with velvet, you’ll notice a grayish or golden film on his body.  You can treat velvet with the same treatment for ich.


Constipation is common enough to affect almost every betta but can be lethal. It is caused by poor diet or lack of exercise, and if left untreated, it can become worse very quickly.

What You’ll Notice:

  • Uncontrolled swimming
  • Loss of appetite 
  • Less poop
  • Lethargy

What You’ll Do:

  • Increase the aquarium’s temperature to 80-82 degrees fahrenheit to improve metabolism.
  • Fast your betta for 72 hours.
  • Boil a single pea, skin it, and feed it to your betta. The fiber should help him pass stool.

Causes and Prevention of Betta Diseases

The most common causes of betta diseases are poor water quality, bad diets, and poor living conditions. When the aquarium fish live under these unfavorable conditions, their immune systems are weakened, making them prone to illness.

Here are a few foolproof tips you can use to create a neat living environment for your bettas:

  • Avoid overfeeding your fish because uneaten food reduces oxygen in the tank and serves as nutrition for unwanted microorganisms.
  • Use an appropriate filter to match your tank’s size and type, making sure to clean the filter media regularly.
  • Tame algae growth by cleaning decorations and rocks, and vacuuming the floor of the aquarium. 
  • As the landlord, you must ensure that your aquarium isn’t overcrowded to avoid stressing your betta tenants. 

Importance of Proper Nutrition and Feeding Practices

Like other fish, bettas can benefit from proper nutrition in many ways. Here are a few ways feeding practices affect your betta’s health:

  • It prevents overfeeding, which can prevent bloat and debris from uneaten food. 
  • Feeding your betta diet-appropriate food boosts their immune system and protects them against illness.
  • With bettas, you get what you give. Protein-rich diets will get you vibrant colors and bouncy bettas.

Disease Prevention Through Regular Water Changes and Tank Maintenance

For our aquatic besties, the water is like the air we humans breathe. It should be clean, free from dangerous organisms, and safe for our health. Bettas endure the same experience with their tank atmosphere, so it is essential to keep it clean.

Here are a few benefits of regular changes and proper tank maintenance:

  • Changing your betta’s water helps to eliminate disease-causing pathogens.
  • It can help dispose of eaten food, which can serve as food for harmful microorganisms. 
  • A clean tank is a safe space for an ill betta to safely recuperate.

Diagnosing Betta Fish Diseases

Betta disease diagnosisSymptoms 
Betta fish fin rotBleeding and discolored fins, frayed fins and tail, swollen scales, and cotton-like growths on the fish
Swim bladder diseaseDifficulty swimming and lopsidedness, floating close to the surface and in one spot
IchSmall, grain-like white spots around fish body, scratching against tank ornaments
DropsyBulgy eyes, swollen belly, scales pointing outward like a pinecone, and pale and stringy feces
Cotton wool diseasePale lesions and slimy cottony growths on fish skin, trouble swimming
Vertical death hangFloating vertically with its mouth facing the surface, struggling to stay buoyant
PopeyesBulgy eyes, surrounded with white rings at the eyes’ corners
TumorVisible bulge protruding from anywhere on fish’s body
VelvetYellow or gold dust-like coating on fish, scratching against tank ornaments
ConstipationLoss of appetite, swollen belly, and stringy feces hanging from the betta

🐠 Pro tip: We can give you a list of possible betta diseases, but only a licensed veterinarian can give you a diagnosis. Consult a vet to give your betta the very best medical care.

Treatment and Care

Here are some options for treatment and care for your betta fish:

Betta diseasesTreatmentsInstructions 
Betta fish fin rotBettafix medicationUse ½ teaspoon per gallon in the hospital tank
Swim bladder diseaseEpsom or aquarium saltAdminister one teaspoon per gallon
IchAPI Liquid Ick Cure Add 1 teaspoon per 5 gallons of aquarium water
DropsyTetra Lifeguard Bacterial and Fungal TreatmentGive one table per 5 gallons of aquarium water for 5 consecutive days
Cotton wool diseaseHikari Betta ReviveAdminister one drop per 16 ounces of aquarium water for 3 consecutive days 
Vertical death hangAquarium or epsom saltAdminister one teaspoon per gallon of aquarium water
PopeyeFritz Aquatics Mardel Maracyn Two Antibacterial MedicationOn the first day, dissolve 2 packets in 10 gallons of water. Then, for the next 4 days, dissolve one packet per 10 gallons
TumorRefresh and control water parameters Seek a diagnosis from your veterinarian
VelvetFritz Mardel CopperSafe MedicationAdminister one teaspoon per 4 gallons of aquarium water
ConstipationPeasBoil and skin one pea, and serve skinless to constipated fish

🐠 Pro tip: Create a stress-free environment by adding plants and natural decorations to your betta’s tank. A sick betta may want to hide and will become stressed if he has nowhere to go.

Save the image below for a handy treatment guide.

Post-Treatment Care and Prevention of Recurrence

Treating a sick betta isn’t the end of the process. Like humans, they need a stable and clean environment to return to skippy health. 

Here are some ways you can care for your betta after treatment to avoid a recurrence:

  • Closely monitor water parameters and use conditioners to keep the aquarium water in optimal conditions. 
  • Dote on your betta after feeding to monitor his eating habits and remove uneaten food .
  • Perform a 25% water change every couple of days to keep the water clean and healthy. 
  • If your veterinarian has prescribed any medication, ensure to complete the doses to strengthen the betta’s immune system.

Frequently Asked Questions 

How Do I Know if my Betta Fish has a Disease?

Different betta illnesses have unique symptoms, but there are a few general signs that tell your betta is under the weather. Look out for lethargy, troubled swimming, lack of appetite, bulging abdomen, and bulging eyes.

What Does a Sick Betta Fish Look Like?

A sick betta looks depressed and malaised. They’ll often refuse to eat, float in one spot, and stay close to the surface.

Can You Heal a Sick Betta Fish?

You can certainly heal a sick betta, but you just have to know what you’re treating. With appropriate medication, your betta could be bouncing in no time. Otherwise, ill-matched drugs can worsen the situation.

What Could be Wrong with my Betta Fish?

It is often tricky to put your finger on what is bullying your betta’s immune system. As a rule of thumb, betta fish fin rot and any form of necrosis signals an infection. And, bulgy eyes and an otherwise fit body indicates pressure, as in Popeyes.

Let’s Review…

When our fishes are ill, we share in their suffering. Our aim is to provide them relief and nurse them back to health, but we can only do that when we know the cause.

Before administering any drugs to your betta, run his symptoms through our comprehensive guide. While some symptoms may seem similar, careful observation can help you tell them apart. Luckily, quality care can help us avoid illness and keep our bettas happy and healthy.

Gift this guide to a fellow fish enthusiast or betta fishkeeper. Remember, sharing is caring!

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