Columnaris: Cotton Mouth Disease In Fish


Last updated on July 4th, 2022 at 11:26 am

Columnaris, also known as cotton mouth disease in fish, is a bacterial infection that can be deadly in fish tanks and aquariums if left untreated. This highly contagious bacterial infection leads to inflammation and ulceration of the mouth and surrounding tissues and has been known to be fatal in some cases.

It can affect any fish, but it can prove especially dangerous to bettas because of their short lifespans and susceptibility to bacterial infections in general.

Columnaris is an extremely common and serious bacterial infection that can cause mortality rates as high as 100 percent if left untreated. If you have freshwater or saltwater fish, columnaris (or cotton mouth) should be at the top of your list of concerns, especially if you keep a community tank with multiple species, and even more so, if they’re all eating out of the same place!

Here’s what you need to know about this condition in order to take quick action at the first sign of its symptoms and how you can keep your fish safe from it.

What causes columnaris in fish?


Columnaris disease is caused by bacteria that affect both freshwater and saltwater fish. It is highly contagious but can be treated with antibiotics. While columbraris isn’t usually fatal if treated promptly, it can weaken a fish’s immune system and make it vulnerable to other infections.

It causes white lesions around a fish’s mouth (hence its name), but other symptoms may include clamped fins and red streaks on their body. These are signs of advanced columnaris and you should seek out treatment for your fish immediately. If left untreated, some cases of columnaris can lead to death within 48 hours!

Water temperature also seems to play a factor in whether or not your fish will get sick; according to online FAQs, cold temperatures cause less stress on your fish and lower water temperatures encourage bacterial growth.

Infectious agent

Columnaris disease (also known as cottonmouth, fin rot, and mouth fungus) is a bacterial infection that can affect many types of freshwater aquarium fishes. Originally described by Bassett and Deibel (1947), it has been identified as Flavobacterium columnare. Infection results in rapid tissue necrosis; particularly vulnerable areas include gills, mouth, fins, skin, and scales.

The bacteria infect healthy tissue through abrasions or cuts on exposed surfaces of the body. High levels of stress also appear to make fish more susceptible to infection, especially when combined with poor water quality.

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Columnaris sometimes appears, following successful treatment for parasites such as ichthyophthirius, or even following treatments for bacterial infections such as fin rot caused by gram-negative bacteria including Aeromonas and Pseudomonas species.

With proper diagnosis and treatment, complete mortality should be avoided.

Where does columnaris come from?

Most cases of columnaris are caused by a type of bacteria called Flavobacterium columnare, but it can also be caused by other types of bacteria. Many cases are actually secondary infections resulting from another disease that lowers a fish’s ability to fight off germs. The disease can also develop as a result of injury or stress.

The best thing you can do to prevent columnaris is to maintain good water quality and avoid placing new fish in an aquarium with sick or weak fish. It’s important to treat any illness promptly if it does occur; medications for treatment include malachite green, kanamycin sulfate, erythromycin, and salt baths.

Freshwater tanks should use 0.5% salt; for every 1 gallon of water, add 1⁄2 teaspoon (2 g) of non-iodized table salt for a 10-gallon tank or 1 teaspoon (4 g) for every 10 gallons in larger tanks.

What are symptoms of columnaris?


Columnaris disease, also known as cotton mouth or ulcer disease, causes inflammation and irritation to a fish’s mouth, gills, and sometimes even internal organs. This leads to a wide range of external symptoms that can include redness around the eyes, rapid breathing or gill movement, swelling of tissue inside of their mouths, and lesions on fins.

If your fish exhibit any of these signs, immediately isolate them from other fish in your tank by moving them into another bare quarantine tank and using freshwater chlorine solution (aquarium salt or potassium permanganate) for at least 24 hours at 1ppm (1 tablespoon per 5 gallons). Continue treatment until no signs are present for at least 5 days. If caught early enough you may be able to treat with antibiotics from your local pet store, Columnaris can be deadly if not treated quickly and properly.

How is columnaris transmitted?


It’s most commonly transmitted through direct contact with another infected fish or through an unclean environment, like an improperly filtered tank. It can also be spread to other aquarium fish through body contact, for example, by sharing nets or bowls.

When it comes to parasite prevention, isolation tanks and quarantine procedures are essential for any new additions to your home aquarium. When you bring a new fish home for the first time, isolate it from your other fish for two weeks before putting it into its permanent home so that you can make sure there isn’t any trace of disease lingering on its fins or gills.

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Just because one fish seems fine doesn’t mean they all are. When you introduce a new fish to your aquarium, assume it has parasites until proven otherwise!

Is columnaris contagious to humans?

Most types of bacteria diseases, including columnaris, can be transmitted to humans. However, you’re most likely to get ill if you handle live infected fish. Because some types of columnaris are transmittable to humans via water and equipment—for example, pet bowls and aquarium nets—you may also be at risk for illness if your aquarium is contaminated or improperly cleaned.

These infections are very rare; even though we know that they can happen, few cases have been documented in the medical literature.

What fish does columnaris affect?


Columnaris disease affects a wide variety of freshwater and saltwater fish. It can be caused by either bacterial or fungal infections, but it usually refers to cases that occur as a result of bacterial infection.

Can columnaris be cured?

Most strains of columnaris are resistant to common antibiotics (such as Trimethoprim, Sulfas, and Tetracycline) but can be treated with erythromycin or a quinolone antibiotic. The treatment should be started early to reduce mortality, but sometimes antibiotics alone aren’t enough and it has to be combined with water changes. Treatments for less severe cases often include raising water temperature, lowering dissolved oxygen, and treating for parasites.

Treating columnaris

First and foremost, don’t freak out. Lots of people tend to overreact when they discover that their fish has been infected by something. It’s always important to do your research before making any decisions on what action you’re going to take, especially when it comes to medication.

A common way of treating this disease is with Maracyn or Maracyn II (which can be purchased at most pet stores). Do not use these medications with goldfish! Other antibiotics like Tetracycline are also helpful if used correctly. To make sure your fish gets better, do a 30% water change every day until the fish seems well again. Continue to feed them as usual too.

Treating columnaris with salt

Columnaris disease can be treated with salt baths. Start by changing half of your tank’s water and add 1 teaspoon of non-iodized salt per 1 gallon of water. Replace their usual food with a commercial brand of flake fish food mixed with one crushed vitamin pill (like Betta Buffet or Omega One). Continue adding more new water with salted water, replacing all dirty water until you have completely changed out about a third to a half of your tank’s total volume.

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Then top off your tank as normal. Be sure to rinse filter media thoroughly before putting it back into service and do not use any activated carbon during treatment; instead, replace it with fresh activated carbon once treatment is complete. The best thing you can do while treating a case of columnaris is to keep up good water quality by doing regular partial water changes each day.

How long does it take for columnaris to go away?

It’s hard to tell how long it will take for your fish to recover from columnaris, especially since some people are more prone to infection than others. The infection typically runs its course in two weeks or less but can take longer if your tank and equipment aren’t properly maintained. If you follow an effective treatment plan, you should see signs of improvement within three days.

Does columnaris cause fin rot?


No, it does not necessarily cause fin rot, and indeed some strains of it do not cause any external signs of disease. But columnaris bacteria can produce toxins that can damage gill tissue, which is what causes most clinical signs such as those described.

Columnaris and other opportunistic bacterial infections are commonly diagnosed when poor water quality or other stressors affect a tank with already-compromised fish. In tanks with healthy, stress-free specimens, fin rot may be caused by another type of bacterium altogether.

Is columnaris in all water?

The cotton mouth affects most aquarium fish. The symptoms of cotton mouth vary depending on species, but all start out with a gaping mouth or cottony white appearance. Aquarists should know what kind of disease your particular species may have by observing your pet’s behavior and environment. If you notice any of these symptoms, it’s important to get treatment immediately before other diseases take root.

Can columnaris survive out of water?

You’ve probably heard that many bacteria, fungi, and parasites can live out of water for extended periods of time. This is because they have a high survival rate inside their hosts, which means if their host dies but they survive, they will live outside a host for much longer than pathogens that don’t thrive as well.

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The cotton mouth disease fits into both of these categories. It can survive quite some time out of water due to its high survival rate inside its hosts. And it thrives very well inside fish; sometimes you may even find your infected betta covered in white patches on his gills or on his body. Since bettas are mostly made up of water, he is more susceptible to secondary infections like columnaris.

Does KanaPlex treat columnaris?

KanaPlex is NOT a treatment for columnaris. At least two of these products (AceFlu, API General Cure) say they are. But neither claims to treat Columnaris directly, they only treat secondary infections that occur when the disease infects your fish tank.

Because of these similarities, it can be easy to confuse both conditions, especially if you don’t know what you’re looking at. To make things worse, many articles will use pictures from one disease as examples for another without any reference as to what they show or how their symptoms differ.

Can erythromycin treat columnaris?

Erythromycin belongs to a class of antibiotics called macrolides. This antibiotic can be used to treat certain bacterial infections, including fish tank diseases. Columnaris disease in tropical and marine fish can be caused by bacteria. The treatment includes salt baths, freshwater dips, and quarantine.

Preventive measures

The cotton mouth disease can be avoided by good aquarium maintenance. However, if your pet does develop symptoms, it’s important to act quickly. Move your infected fish to a separate aquarium, keep an eye on water parameters and perform a 25-50% water change every 24 hours.

Consider using a product such as AquariProtect Plus. If things don’t turn around within five days, seek out professional advice from your local fish store or veterinarian. In some cases of advanced infection – particularly with scaleless fish like goldfish – amputation might be required; however, recovery is unlikely after just one limb has been removed from such species.