Columnaris In Bettas (Cotton Wool Disease Cure)

Last Updated on 2024-05-25

Columnaris in bettas is a fairly common infection, so you need to be on alert to make sure your betta doesn’t catch it. If you think your betta has columnaris the knowing as much information as possible could be the difference between life and death. Keep reading to find out the symptoms, treatment and prevention methods for columnaris.

What Is Columnaris?

Columnaris is a bacterial infection that can affect all fish in your tank. It goes by many names such as cotton wool disease, cotton mouth disease, saddleback disease, and guppy disease. It’s more commonly found in livebearers but that doesn’t mean your betta won’t catch it. It’s called columnaris because the bacteria that cause it are columnar in shape.

Columnaris is able to enter your betta in a number of different ways such as the mouth and gills, and open sores.

What Causes Columnaris?

There are a lot of different factors in play that causes columnaris to occur. For example, it can be in your tank but if your betta has a strong immune system then it is less likely to become infected. Here are the most common causes to watch out for:

  • High bioloads/overstocking – If your overstocking your tank with fish then the bioload is going to be too high. Your filter won’t be able to efficiently deal with all the waste in the tank and the water quality will become poor. The poor water quality will then be a breeding ground for all types of bacteria. And eventually, columnaris or another sickness will infect your betta.
  • Harassment by other fish – Bad interactions with other fish can also cause columnaris to occur.  The stress from these encounters causes a bettas immune system to become weakened. With a weakened immune system, they’re more susceptible to infections and diseases.
  • Fluctuating water temperature and pH levels – Both of these are also going to stress your betta out. And the added stress is going to compromise their immune system.
  • Poor Water Quality – A tank doesn’t have to be overstocked for the water quality to be poor. If you’re not performing regular water changes and not cleaning it regularly, the water quality will also drop.
  • Carried in from another tank – This is one of the reasons it’s so important to quarantine your fish when they’re new. Otherwise, you risk introducing a fish which is harboring an illness or disease.
  • Poor diet – And lastly, if your betta has a poor diet then it’s immune system is going to be weak.

What Are The Symptoms Of Columnaris In Bettas?

Columnaris is easily noticeable by the cotton-like growths on the body of your betta. However, that’s not always going to be the first thing you will notice. Here are symptoms that you should look out for.

  • The first thing you’re likely to notice is frayed and ragged fins. However, this is also similar to fin rot. (Fin rot causes the fins to fall apart, once the fins are all gone the body will also begin to rot away. You can find out more about it in this article about fin rot!)
  • After the fraying fins, you will begin to notice ulcerations and sores on your bettas skin. This will let you know that your betta is suffering from columnaris and not fin rot.
  • You’ll also begin to notice white growths on your betta that look cloudy or like cotton. (Find out other reasons your betta may be turning white.) Most often you’ll notice this around your bettas gills and mouth. But sometimes it will also go across their back resembling a saddle. However, these growths can occur on any part of the body. (It’s also important at this point that you’re not mistaking columnaris for ich. Ich or ‘white spot disease’ looks similar but depending on its cause may need a different type of treatment.)
  • In the final stages, your bettas gills will change color. They will start to look brown. It’s at this point that columnaris becomes a lot harder to treat. The skin around the gills is beginning to die and necrosis sets in. Your betta will also show signs of labor as well as rapid breathing to try and help it get oxygen in.

Other Symptoms Of Columnaris In Bettas

While these are the most severe symptoms you will notice in your betta there are also other ones to look out for. When you notice these symptoms they will help you diagnose your betta correctly.

  • The gills, mouth, head and the dorsal area will begin to be covered in mucus. This is your bettas immune system doing everything it can to try and get the columnaris off its skin and out of its system.
  • Your bettas lips can also become swollen and if left long enough, they’ll start to rot away.
  • Because their mouths become infected they also lose their appetite and may refuse to eat altogether.
  • Bettas will also try to rub their bodies against ornaments in the tank and the gravel. This is an attempt to try and remove the infection from their skin.
  • A more general symptom is that they’ll start to lose their color. However, this happens whenever your betta is sick and may not be directly related to columnaris

In really extreme cases, your bettas head will get eaten away. If your betta has reached this stage of columnaris infection, then the best thing you can do is euthanize him. Otherwise, you’ll draw out a long and painful death.

(If you don’t notice these symptoms in your betta, then they may be suffering from something else! Check out this article on all the diseases and illnesses your betta can end up suffering from.)

How To Treat Columnaris In Bettas

It’s not all doom and gloom. If you’ve spotted columnaris early enough then your betta can make a full recovery! Follow the steps below to give your betta a fighting chance of recovering and living a healthy life.

  1. Before anything else, you should move your betta to a quarantine tank. (Here’s everything you need to know about quarantine tanks, including how to set them up.)
  2. Make sure your quarantine tank has nothing your betta is going to damage himself on. Also, you’re going to want to fill the tank with conditioned tap water.
  3. Even though a betta’s ideal temperature is 78°F when dealing with columnaris you should lower the temperature to 75°F. Columnaris thrives in warmer temperatures, so around 75°F is going to make it harder for the bacteria to stay alive and reproduce.
  4. Now that the temperature of your tank is right, you should begin using an antibiotic to treat your betta. Furan 2 is a great choice, and to use it you should follow the instructions on the bottle or speak to a professional.
  5. As well as using Furan 2 you should also add aquarium salt. This is going to help reduce his stress and strengthen his immune system. Once again make sure you read the instructions before using aquarium salt, but 1 teaspoon per 5 gallons is an adequate amount.
  6. When using Furan 2 & Aquarium Salt make sure you’re performing a 100% water change before redosing, or you could end up doing more damage to your betta.
  7. While you’re treating your betta you should also be performing 25% water changes every 3 or 4 days in your main tank. This is going to help remove any traces of columnaris from your tank.

If you follow these steps and you’ve caught columnaris early enough then you should notice your betta improving after a few days. However, if your betta seems to be deteriorating then you’ll need to swap to a stronger antibiotic like Kanamycin.

You can also try combining Kanaplex with Furan 2, however, be warned this will affect the biological filter in your tank, so you will have to perform more water changes with this treatment.

How To Prevent Columnaris In Bettas

As the age-old saying goes an ounce of prevention is worth a pound of cure. The real way to handle a columnaris outbreak in your tank is to stop it from happening. Here are a few ways you can prevent columnaris infections in your betta and tank.

  • Make sure that your tank isn’t overcrowded – One of the biggest causes of columnaris is when a tank is too overcrowded. When this happens then the waste and bacteria will build up quicker than you and your filter can get rid of it. As a rule of thumb, you should have 1 gallon per inch of fish in your tank. (However, bigger fish will need more space.)
  • Clean your tank regularly – Cleaning your tank seems like a pain when the water looks fine. But even if the water is crystal clear it can still be teeming with dangerous bacteria. You should regularly remove any algae from your tank as well as vacuum the gravel. Fish waste that sinks to the bottom of the tank becomes the perfect breeding ground for bacteria.
  • Perform regular water changes – No matter what size your tank is you should be performing regular water changes. The smaller the tank the more water you’ll have to change as well as the more frequently you’ll have to change it.
  • Quarantine any new fish – If you plan on adding new fish to your tank then you should quarantine them for a month beforehand. This way there’s a good chance you’ll find out if they’re infected as well as liming the chance of any bacteria transferring to your main tank.
  • Disinfect equipment that’s been used before – If you’ve used any equipment to treat sick fish before then make sure you disinfect it thoroughly before using it again. It only takes reintroduction one time for your tank to become completely flooded with bacteria.
  • Make sure your fish aren’t being aggressive – If your betta is being aggressive to other fish, or other fish are being aggressive towards your betta then remove the culprit as soon as you can. Aggressive fish are going to weaken the immune systems of all the other fish. And with a weakened immune system, your betta will be more susceptible to columnaris.
  • Feed your betta a balanced diet – Bettas need a lot of meat in their diet. Without enough meat, they can become malnourished. And if they’re malnourished then they’re more likely to get suffer from columnaris as well as many other infections.

Wondering where you can find a comprehensive guide on Betta fish care? Click here!


If you think your betta has columnaris all hope isn’t lost. If you follow the advice above and if you’ve caught it early enough then your betta should make a full recovery. Here are some of the main points you should try and remember:

  • Columnaris can go by many different names including saddle back disease, guppy disease, cotton mouth disease, and cotton wool disease.
  • Common causes of columnaris include an overcrowded tank, poor water quality, malnutrition, and stress.
  • The symptoms of columnaris are frayed and ragged fins, cotton-like growths on your betta, gills turning brown, mouth swelling and sometimes detaching, lethargy and lack of appetite.
  • To treat columnaris make sure you lower the temperature of your tank to 75°F and use medicine such as Furan 2 or Kanaplex
  • To prevent columnaris in your tank make sure you keep the water quality good, feed your betta properly, clean your tank regularly and quarantine any new fish.

If you follow all of these steps then you’re going to stop your betta and any other fish suffering from columnaris!

If you have any more questions then leave them below! Otherwise, have a great day!

If you think your betta may be suffering from another illness then check out the links below:

    • Ich In Bettas – Ich is similar to columnaris however, it’s going to require a different treatment. If you want to know how to spot the differences then read this article!

    • Fin Rot In Bettas – Fin rot can often be mistaken for the early signs of columnaris. If your betta has fin rot then it’s going to take some time for him to recover fully. However, you can speed up the process

    •  Swim Bladder Disease – If you notice your betta can no longer swim properly then he may have swim bladder disease. Swim bladder disease has many different causes and diagnosing the right one is the key to keeping your betta alive!

    • Dropsy In Bettas – If your betta has dropsy then sometimes it’s often the best course of action to euthanize him. However, if you still think he has a fighting chance then this guide will tell you what you need to do!

    • Cloudy Eye In Bettas – Cloudy eye is one of the less severe illnesses your betta is susceptible to. But if you leave it untreated it can often cause blindness and even the loss of eyes altogether. With the right treatment, you’re going to be able to stop that happening!

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2 thoughts on “Columnaris In Bettas (Cotton Wool Disease Cure)”

  1. Hello,

    I have a betta who has developed, over several months, a white growth on his head. I have tried basic water changes with some aquarium salt and Melafix and, more recently, Furan-2, to try to rid him of it. Nothing has worked so far. I have several photos I can send. Was hoping maybe you might be able to take a look and see what you think could be afflicting him?

    He seems to be acting fine, has good color, is eating and doesn’t have any other marks on him that I can see (or fin rot or that sort of thing).

    I greatly appreciate your help! 🙂



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