What Do Unhealthy Betta Fish Look Like? Disease Symptoms & Treatments

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Aquarium experts explain how to diagnose & treat betta fish illnesses

Co-authored by Craig Morton and Devin McSween

Last Updated: April 4, 2025 Fact Checked

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• General Symptoms
|
• Fin/Tail Rot & Fungal Infections
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• Velvet
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• Ich
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• Popeye
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• Dropsy
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• Swim Bladder Disease
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• Hole in the Head
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• Constipation
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• Keeping Your Betta Healthy
|
• Video
|
• Expert Q&A

|Show more |Show less

While betta fish are pretty easy to care for, they can sometimes grow unhealthy or catch diseases, causing them to get sick. To help you tell if your fish is sick or not, we asked several aquarium experts to explain the signs of an unhealthy betta. These experts also explained how to diagnose and treat common diseases affecting betta fish, as well as how to keep your fish happy and healthy. Read on to learn more!

Common Symptoms of Sick Betta Fish

Sick or unhealthy betta fish may show faded coloring, lethargy, and a refusal to eat. Signs of infections often include torn fins, white spots, cloudy eyes, and/or bulging eyes. A swollen stomach and raised scales can also be symptoms of the disease dropsy.

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Section 1 of 10:

Signs of Healthy vs. Unhealthy Betta Fish

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1. 
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   Faded or dull coloring When a betta gets sick, their coloring may look faded, dull, or pale. They may even lose their color altogether.

   • Healthy betta fish have bright and vibrant coloring.
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   Damaged or clamped fins According to aquarium specialist Craig Morton, an unhealthy betta may develop holes or rips in their fins. He also says their fins might appear clamped or tethered to their body—in other words, they aren't fanned out properly.

   • Healthy betta fish have long, damage-free fins. They gracefully fan out from their body and flow as they swim.
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   Lethargy and low activity level If your betta is sick, their activity level will likely decrease; they won't be their normal, active self. Their movements may slow down and you might even catch them lying motionless on the ground.

   • Healthy betta fish are very active and curious about what you’re doing.
   • Another sign of sickness is your fish hiding out at the bottom of the tank more often than normal. They might avoid interaction or retreat when you approach.
   • Lethargy can be caused by other things besides sickness, like a too low or high temperature. So, make sure your providing your fish with the conditions and care they need—we discuss how best to keep your betta fish happy in the sections below!
4. 
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   Decreased appetite With some sicknesses, your betta fish may appear uninterested in food. They might even stop eating altogether.

   • Healthy betta fish are usually very eager to eat and don’t miss a meal time.
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   Trouble swimming If your betta fish is sick or unhealthy, they may swim abnormally. For instance, they might swim upside down, swim on their side, have trouble staying upright, or even sink to the bottom of the tank.

   • Healthy betta fish are active, graceful swimmers that easily stay upright and glide through the water.
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   Breathing problems It may sound funny to check a fish for breathing problems. However, if your betta is constantly at the top of the tank trying to get more air or even gasping for breath, that is likely a sign of a problem.

   • Healthy betta fish naturally go to the top of the tank to take a breather at times, but doing it frequently is abnormal.
   • According to aquarium expert Wes Corbyn, it’s normal for bettas to swim to the surface because they “have a labyrinth organ” that “allows them to breathe surface air.”
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   White spots Morton says sick betta fish sometimes develop small, white spots on their body, especially around the head and mouth, as well as a white film.

   • Healthy betta fish typically have clean, clear skin that’s free from spots or film.
   • This symptom can be a sign of a certain type of parasite, called Ich.
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   Rubbing or scratching behaviors Aquarium expert Cyriac St.Vil says if your betta tries to rub against the side of the tank or “purposely runs into objects in the tank,” they “may be showing signs of illness.” Similarly, if your betta is trying to scratch on plants or objects in the tank, they might also be unhealthy.

   • Healthy betta fish typically swim freely without rubbing or scratching themselves on objects in the tank.
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   Cloudy, bulging eyes and other physical symptoms According to Morton, cloudy eyes can be a sign of illness, as healthy bettas have clear, bright eyes. Bulging eyes can also be a sign of sickness. Watch for your betta's eyes protruding from its head.

   • More physical symptoms include:
     • Raised scales: Raised or pinecone-looking scales can be a symptom of sickness in bettas, as their scales are smooth and flat when they’re healthy.
     • Swelling: A sick or unhealthy betta may have a swollen belly or other bulging spots on their body. Healthy bettas have smooth, bump-free skin.
     • Gill problems: If your betta is unable to close their gills, they may be swollen, which is another sign of sickness. A healthy fish can easily open and close their gills.
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Section 2 of 10:

Diagnosing and Treating Fin/Tail Rot & Fungal Infections

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   Look for deteriorating tails and fins to diagnose fin/tail rot. According to aquarium expert Marshall Stephens, the most common symptom of fin/tail rot is “deteriorated fins” or tails that have a shredded or torn appearance. He says there might also be “redness of the fins” and a “white cotton-like growth.”

   • Also, look for darker coloring near the end of the tail.
   • Be aware that some longer-tailed varieties, such as halfmoon bettas, may try to bite their fins because they are too heavy. In this case, look for other symptoms of sickness as well as torn fins.
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   Watch for white patches to diagnose a fungal infection. Stephens says the most common symptoms of a fungal infection are “cotton-like growths around the mouth and fins.” He says you might also notice “red streaks in the fins.” Your fish might also have clumpy fins or be less active than normal.

   • While a fungal infection is different from fin/tail rot, they are treated in much the same way.
   EXPERT TIP

   

   Brian Blake

   Aquarium Expert

   Brian Blake is an Aquarium Expert and the Owner of Boodleshire Aquatics based in the Kansas City Metro Area. With over 20 years of experience, Brian is an expert in freshwater planted aquariums, saltwater reef aquariums, and aquarium installation, care, and maintenance. Brian holds a Bachelor's degree in Ichthyology and Aquatic Environmental Science from Emporia State University.

   

   Brian Blake
   Aquarium Expert

   Look for multiple symptoms to properly diagnose a betta. A single symptom can be the result of several illnesses. For instance, white patches can be a sign of a fungal, bacterial, or parasitic infection. Noticing other bacterial infection symptoms, like cloudy eyes, might mean the patches aren’t fungal.
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   Change the water to treat your fish. If you suspect your fish has an infection, Morton says the first step is to change out the water. Of course, you need to remove your fish and put it in a holding container while doing so. Fin/tail rot and fungal infections often develop from dirty water, so you need to provide a clean environment for your fish. Also clean the tank before putting fresh water back in.

   • To remove the water in the tank, Morton suggests you use a hose to siphon out the dirty water.
   • Remove the decorations and gravel. St.Vil suggests soaking them in “1 part water and 3 parts vinegar” for 1 hour. Then, rinse them off thoroughly.
     • For any rocks, bake them at 450 °F (232 °C) for 1 hour. Let them cool before adding them back to the tank.
   • Clean out the tank with bleach and water. St.Vil recommends a solution of “1 part bleach and 5 parts water.” Then, rinse out the tank several times.
   • Fill the tank with fresh water and add a water conditioner. Allow your fish to acclimate to the water before directly putting them back in the tank.
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   Add a medication into the water. To treat fin/tail rot, Morton suggests adding API BettaFix medication to the water. You can also give your betta ampicillin or tetracycline, which you add to the water. How much you add depends on the size of the tank—simply follow the directions on the package.

   • If your betta just has a fungal infection, they won't need tetracycline or ampicillin. Instead, add a fungus eliminator to the water. This helps keep the fungus out of the water.
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   Repeatedly change the water and add medication. Change the water at least every 3 days. Every time you change the water, add the medication back in. Only stop when your betta fish’s fins or tail seem to be growing back in, which can take up to a month.

   • For fungal infections, look for the white patches and other symptoms to disappear. When they do, treat the tank with BettaFix to help eliminate the fungus.
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Section 3 of 10:

Diagnosing and Treating Velvet

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   Look for a gold or rust-colored sheen on your fish. One of the best ways to diagnose velvet is to shine a flashlight directly on your fish. This will help you see the shimmer of gold or rust that this disease can produce on the scales. Your fish might exhibit other symptoms, such as lethargy, loss of appetite, clamped fins, and rubbing or scratching themselves against walls or items in the aquarium.

   • Velvet is a parasitic infection.
   • This parasite can be prevented by adding aquarium salt and water conditioner to your tank on a regular basis. Add 1 tsp (6 g) of aquarium salt for every 2 ½ gallons (9 L) of water. You also need 1 drop of water conditioner per 1 gallon (3.8 L), though always read the instructions that come with your water conditioner.
     • Only add extra salt when doing water changes, not when topping off a tank.
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   Separate the sick fish and use BettaFix to treat velvet. If your betta is in an aquarium with other fish, place your fish in a separate tank. Then, follow the directions on the bottle of BettaFix to add the correct amount to your fish’s water.

   • Alternatively, use a medication like Seachem Cupramine, Methylene Blue, or Maracide.
   • Continue adding medicine until your fish no longer exhibits symptoms of velvet. Simply check the medication’s packaging to see how often to add it to the tank.
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   Treat the whole tank with BettaFix to prevent velvet from spreading. If your betta lives with other fish, it’s a good idea to treat the entire tank for velvet. Velvet is a very contagious disease, so it could have spread to your other fish. Simply follow the directions on the bottle of BettaFix to add the correct amount to the community tank.
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Section 4 of 10:

Diagnosing and Treating Ich

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   Look for white spots all over the body that look like salt. Ich is a parasite that produces small, white spots on your fish’s body, says St.Vil. Also, look for clamped fins and lethargy. Your fish may also stop eating.

   • Like velvet, this parasite is preventable if you treat the water right. St.Vil suggests doing “regular water changes and regular filter media changes” to prevent ich.
   • Regularly adding aquarium salt or water conditioner to your tank can also help prevent ich. Always read the directions on the product to add the correct amount into your tank.
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   Raise the temperature to treat ich in large tanks. If you have a large community tank over 5 gallons (19 L), raising the temperature to 85°F (29°C) can kill off the parasite. Just don't do this if your tank is smaller, as increasing the temperature can overheat the tank and kill your fish.
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   Clean the tank and change the water. Ich thrives in dirty water, so it’s important to clean the water and tank. Siphon out the dirty water, disinfect the tank and decorations, and add in fresh, conditioned water. To help ensure the parasite is gone, heat the water to 85°F (29°C) before putting the fish back in the tank.

   • Be sure to treat the new water with water conditioner or aquarium salt before returning your fish to the tank. This helps keep the tank from reintroducing the parasite.
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   Add an ich medication to the water, like Tetra Ick Guard. Ich medications kill off the parasite and help prevent other infections from forming. Simply follow the directions on the medication for the proper dosage and how often to add it. Some other common medications include API Super Ick Cure and Kordon Ich Attack.

   • BettaFix can also be used in a pinch.
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Section 5 of 10:

Diagnosing and Treating Popeye

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1. 
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   Look for bulging eyes to diagnose popeye. Blake says “popeye is a symptom of a bacterial infection.” He says “when a fish becomes infected with bacteria in the eye,” oftentimes “the buildup of gas from the bacteria…results in the eye popping out.” So, look for either of your fish’s eyes to bulge or protrude from their head.

   • Blake notes that fish often develop popeye due to a weakened immune system, which might be “because of dirty tank water or improper water conditions,” like too cool or hot water.
   • Popeye can sometimes be a symptom of other diseases, such as tuberculosis. Unfortunately, there is no cure for betta fish tuberculosis.
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   Clean the tank and change the water. To treat popeye, siphon out the dirty water and sanitize the tank, decorations, and gravel. Then, add conditioner to some fresh water and pour it into the clean tank.

   • Continue to change out the water every 3 days until you notice your fish getting better.
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   Add ampicillin into the water. Ampicillin helps treat popeye that’s caused by bacterial infections. Simply add this medication to the water every time you change the water—simply follow the directions on the bottle for how much to add.

   • Continue this regimen for 1 week after you stop seeing signs of the problem.
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Section 6 of 10:

Diagnosing and Treating Dropsy

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1. 
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   Look for swelling and raised scales to diagnose dropsy. Dropsy is typically caused by an infection in your fish’s abdominal organs, which causes their belly to swell and bulge. This disease can also cause your fish’s scales to stick out, giving them the appearance of a pinecone.
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   Isolate your fish and add Epsom salt into the tank. Place your fish in a separate tank if they’re in a shared aquarium. Then, Morton recommends adding “2.5 teaspoons (12.5 g) of Epsom salt” for every “ten gallons (37.8 L)” of water in the tank to help cure dropsy.

   • Change the water every few days and add more salt until your fish starts to recover.
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   Feed your fish antibacterial fish food. Morton also recommends feeding your fish antibacterial fish food to help cure dropsy. Replacing their regular food with food containing antibiotics can help kill off the bacterial or parasitic infection causing dropsy.
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Section 7 of 10:

Diagnosing and Treating Swim Bladder Disease

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1. 
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   Look for sinking or an inability to swim to diagnose swim bladder. Swim bladder disease affects your betta fish’s swim bladder organ, which helps them float and swim properly. So, if they have this disease, you might notice them having trouble swimming upright, floating upside down, or sinking to the bottom of the tank.
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   Reduce feeding. Swim bladder disease is often caused by overfeeding. If your fish is eating normally (not refusing to eat or acting disinterested in food), skip feeding them for 1 day. This can help their digestive system reset and reduce the swelling causing swim bladder disease.
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   Change the water and add salt. Swim bladder disease can also be caused by a bacterial infection. So, it’s a good idea to siphon out the dirty water, clean the tank and decorations, and add in fresh, conditioned water. Morton also recommends adding “2 teaspoons (12 g) of non-iodized salt” and 2 teaspoons (12 g) of “Epsom salt per gallon (3.8 L) to the aquarium.”

   • If your betta fish is in a communal tank, place them in a separate tank for treatment.
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Section 8 of 10:

Diagnosing and Treating Hole in the Head

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1. 1
   Look for holes or pits around your fish’s head. Hole in the head disease results in holes and pits around your fish’s head and eyes. It can also cause your fish’s flesh to erode away. You might also notice your fish acting lethargic.
2. 2
   Change and treat the water. Hole in the head can be caused by many things, but it's often due to a bacterial infection. So, siphon out the dirty water and replace it with fresh, conditioned water. Then, treat the water with a general medication that kills off bacteria and parasites, like API General Cure.
3. 3
   Feed your fish high-quality food. Hole in the head can also be caused by nutritional deficiencies. Ensure your fish is getting all the vitamins and nutrients they need by giving them high quality betta fish pellets.
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Section 9 of 10:

Dealing with Constipation

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1. 1
   Look for signs of swelling. If your betta fish suddenly swells, they may be constipated. It’s important to treat this problem soon.

   • Note: Constipation can look similar to swim bladder disease. If treating them for constipation does not help, follow the methods for curing swim bladder disease.
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   Stop feeding your fish for 1 whole day. The best way to help constipation is to stop your fish’s regular diet for 1 day. This will give them time to digest and move food through their system.
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   Feed your fish live food after fasting them. For instance, feed your betta brine shrimp or blood worms. According to Stephens, the general rule on how much food to give tropical fish, like bettas, is “not more than they can eat in about 30 seconds.” Make sure you feed your fish about twice per day.

   • Another great option is to feed your betta fish peas, as they contain fiber that can reduce constipation. Simply cut a few peas into tiny pieces.
4. 4
   Don't feed your fish as much. Constipation is generally a sign you are feeding your betta too much food. Therefore, once they start eating normally again, you need to feed them less than you were.
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Section 10 of 10:

How to Keep Your Betta Fish Healthy

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1. 1
   Change the water weekly. To keep your betta fish happy and healthy, Morton says to “change 20-25% of the water every week.” This helps ensure that the water stays clean and free from bacteria, parasites, and fungi that cause diseases.
2. 2
   Keep the water warm, around 76-82°F (24-28°C). Bettas are tropical, warm-water fish that thrive in temperatures between 76-82°F (24-28°C). To ensure your betta fish stays warm, Morton recommends adding an aquarium heater to your tank to keep the water temperature consistent.

   • Exposure to cooler temperatures can stress your betta fish out and weaken their immune system, making them more vulnerable to diseases.
3. 3
   Add a filter to your tank if you don’t have one. Because betta fish have a labyrinth organ that allows them to breathe air, they can technically live in a tank without a filter. However, Corbyn says betta fish tend to “live healthier, longer lives in a tank with a filter.” Simply add a small filter with a gentle flow to keep the tank nicely oxygenated.
4. 4
   Give your betta fish high-quality food. Ensure your betta fish gets the nutrients they need by feeding them high-quality betta fish pellets. For instance, Morton suggests brands like Hikari Betta Bio-Gold, Tetra BettaMin, and API Betta Food.

   • Feed your betta fish twice per day, once in the morning and once in the evening.
   • Make sure you don’t overfeed your fish, as this can cause them to get ill. Morton says to remember that “the size of the fish’s eye is the size of the stomach.”
5. 5
   Decorate your fish’s tank and keep it in a calm location. Constant stress can also harm your betta fish, so ensure their tank is set up to their liking. Corbyn recommends adding “a few live plants with a small light” to the tank to create a natural environment and give your fish a place to hide and rest. If your fish seems stressed, St.Vil suggests removing distractions, like mirrors, from around the tank and ensuring the space is free from light or noise disruptions.
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Expert Q&A

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• Question

  How often should I change the water in the tank?

  

  Craig Morton
  Aquarium Specialist, Aquarium Doctor Inc.

  Craig Morton is the CEO of Aquarium Doctor Inc. based in Huntington Beach California and servicing Orange County, Los Angeles County, and the Inland Empire. With over 30 years of aquarium experience, Craig specializes in creating custom aquarium designs along with aquarium installation, service, and maintenance.

  

  Craig Morton

  Aquarium Specialist, Aquarium Doctor Inc.

  Expert Answer

  You should change 25 percent of the water in the tank every 2 weeks to keep your fish healthy.

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• Question

  How can I keep my betta fish warm?

  

  Craig Morton
  Aquarium Specialist, Aquarium Doctor Inc.

  Craig Morton is the CEO of Aquarium Doctor Inc. based in Huntington Beach California and servicing Orange County, Los Angeles County, and the Inland Empire. With over 30 years of aquarium experience, Craig specializes in creating custom aquarium designs along with aquarium installation, service, and maintenance.

  

  Craig Morton

  Aquarium Specialist, Aquarium Doctor Inc.

  Expert Answer

  I recommend using either a pad type heater for small fish bowls or a probe heater for larger aquariums.

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  Thank you for your feedback.
  If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow

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• Question

  What medication can I use to treat fin rot?

  

  Craig Morton
  Aquarium Specialist, Aquarium Doctor Inc.

  Craig Morton is the CEO of Aquarium Doctor Inc. based in Huntington Beach California and servicing Orange County, Los Angeles County, and the Inland Empire. With over 30 years of aquarium experience, Craig specializes in creating custom aquarium designs along with aquarium installation, service, and maintenance.

  

  Craig Morton

  Aquarium Specialist, Aquarium Doctor Inc.

  Expert Answer

  API Bettafix is a medication you can buy in stores that will help cure fin rot.

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  Thank you for your feedback.
  If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow

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Tips

• Don't fret if your betta is changing colors. This is known as marbling and happens in most betta splendens. The only instances where changing colors may be a sign of sickness are when your fish fades or turns a paler shade of its previous color. This usually indicates that they are stressed or have a disease (like fin rot).
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• Tears in the fins may be due to rough rocks in the tank or plastic plants, so remove these. Keep the water in the tank warm and clean and your Betta will heal itself.
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• If a Betta is laying down a lot, this may be due to an infection or because they’re bored, unhappy, or hungry. Ensure your fish’s needs are being met before treating them with medication.
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Tips from our Readers

The advice in this section is based on the lived experiences of wikiHow readers like you. If you have a helpful tip you’d like to share on wikiHow, please submit it in the field below.

• If you are unable to diagnose your betta's illness based on the visible symptoms, or if the disease resists standard treatments, an exotic fish veterinarian is your best resource. Veterinarians can identify more obscure diseases through laboratory testing, and also provide access to prescription medications not available over-the-counter.
• To prevent the spread of disease to your fish, always quarantine any new fish in a separate tank for several weeks before adding them to your main aquarium. Since some illnesses have long incubation periods without noticeable symptoms, quarantining lets you observe new fish for signs of disease. That protects your other fish.
• You should never treat your betta fish with disease medications without first properly diagnosing the specific illness. Bombarding fish with random antibiotic or antifungal treatments can be dangerous, or even counterproductive. It may also promote antibiotic-resistant superbugs.
• While dirty aquarium water easily spreads disease, do not overclean the tank by completely changing all the water and scrubbing too vigorously. That can remove helpful bacteria and crash the nitrogen cycle, further stressing your fish.
• Regularly test the water chemistry with liquid test kits instead of unreliable test strips. Improper pH, ammonia, nitrites or other imbalances stress fish and compromise immune systems, making them far more vulnerable to disease.
• Research all common betta fish diseases so you can recognize the symptoms early. The sooner you identify the illness, the faster you can start treatment, greatly improving recovery outcomes for your fish.

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Warnings

• Beware of fish tuberculosis (Mycobacterium marinum). It is contagious and fatal in fish, and can be spread to humans. Symptoms in fish include: Lethargy, popeye, and deformed skeleton/bent spine. Symptoms in humans: Large cyst-like red lump, usually where the bacteria entered (i.e., open cut). If you think you have fish TB, go to your doctor and specify that you own fish, or your doctor might misdiagnose you.
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• Some "symptoms" aren't actually symptoms of a disease. For instance, lethargy can be caused by low temperature (no heater) and rips/tears in the fins can be from sharp objects. Don't just put in medication because one symptom of a disease is present! Look for other clues as well.
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