How To Recognize And 4 Steps To Treat Columnaris Cory Catfish

An aquarium fish can develop a bacterial infection called columnaris cory catfish which can either be external or internal and can follow a chronic or acute course.

Columnarisbacteria, also known as Flavobacterium columnare, is often mistaken for a fungal infection due to their mould-like symptoms.

However, they are easily treated with antibiotics and prevented by following basic maintenance procedures.

How Is Columnaris Defined?

It is unfortunate that this disease is being misrepresented so heavily on the Internet, even on sites like Wikipedia. Hopefully, we can clear up a few misconceptions.

To be more precise, Flavobacterium columnare, which is a bacteria, causes columnaris.

Do not be alarmed, you do not need to keep this name in your mind! There are two names for columnaris that are used by everyone in fishkeeping, columnaris and Saddleback disease.

There are a number of small bacteria in Columnaris. The bacteria are really tiny. They are so small that your only way to see them is with a microscope.

As an illustration, here is a rainbow trout’s gill covered in columns caused by the columnaris fungus…

Observing the bacteria under a microscope, it is evident that they are shaped like rods or columns – yep, that’s how this species got its name.

In the wild and in aquariums, Columnaris is primarily a disease of freshwater fish. In aquariums of saltwater, Columnaris has no place to live.

Almost any freshwater fish species, which resides in fresh or salt water, has the potential to be infected by this fungus.

A fish that is not treated for Columnaris, will die as soon as it is discovered.

Often, a columnaris bacterial infection leads to the death of your fish within a few days of the sign – sometimes even before you notice any signs at all.

You need to start antibiotic treatment as soon as possible if your fish’s outward symptoms correspond to those of columnaris.

There is also a great deal of contagiousness between the fish when it comes to Columnaris. The likelihood of each fish in your tank coming down with it is very high, so all the other one in the tank is at risk as well.

Human beings, thankfully, are not susceptible to columnaris. This means that an infected fish will not infect you or your family members.

What Is The Process Of Bringing Columnaris Into Your Aquarium?

What makes columnaris interesting is:

Your aquarium already has it! It’s already there, so go check it out!

There is no doubt that it is just lingering around, waiting for the perfect moment to strike.

Columnaris are found in water systems and ponds throughout the world. It occurs in everything from small aquariums to large commercial operations, wherever there are freshwater aquatics.

It is indeed a great concern that columnaris are spreading rapidly through the fishing industry since the disease is highly contagious and can annihilate large amounts of fish very quickly.

While there exists a risk of columnaris being present in every aquarium, as explained later in this guide, there is a very specific, and preventable, circumstance in which it poses a threat to your fish.

What Is The Best Method For Identifying Columnaris?

There are many different fungal diseases that are often confused with columnaris

There are many different fungal diseases that are often confused with columnaris, and the most common ones are cotton wool disease or cottonmouth disease.

You shouldn’t be confused about columnaris as there are small tufts of cottony stuff that look like white bread mould, although they are definitely not columnaris.

A defining characteristic of columnaris that makes it difficult to identify is the manner in which it appears, which varies depending on the severity of the condition.

Further complicating matters, different strains may also look and act in a different way from one another.

There are two main categories of Columnaris strains, fast and slow, and it is important to understand how each strain differs from the other.

It has been found that fast columnaris can kill your fish within 24 hours. The majority of the time, you won’t notice any outward symptoms that indicate that your fish has died until it has gone.

It is best to deal with a slow strain of this disease if your fish is still alive and showing the following symptoms. It is still deadly, but if you catch it as soon as possible you should be able to treat it.

This disease causes patches of white spots and or off-colors on the body of your fish that will begin to appear as columnaris develops.

It is also common to see the surrounding scales becoming more washout-looking as the infection grows.

There is a great deal of variation in the color of the infection depending on how badly it has advanced in your fish and the species.

It can sometimes be yellow or orange depending on where it grows, but most commonly, it is very obvious when it is white.

These discolored patches are not fluffy or bumpy; rather, they will be flat.

When left untreated, an infection like this can devour your fish’s scales and skin, especially if it persists for a long period of time.

This is the moment when the skin splits, the scales flake off, the skin turns white and the skin starts to fall off.

There are also long filaments of bacteria that form with the fish disease, which can also be seen with the naked eye.

The columnaris disease is often misdiagnosed as a fish fungus at this stage, which is why most people are unaware of it.

As the bacteria eat their way through the skin of the fish, revealing the muscles beneath, they appear bright red and bloody, as the bacteria continue to eat through the skin of the fish.

Columnaris will result in your fish eating a hole in the middle if left untreated. 

Any part of your fish can be affected by this.

On a rare occasion, a fish may appear sick with a distinctive round patch behind the dorsal fin of its body.

Isn’t it interesting to realize that the occurrence of columnaris is sometimes referred to as saddleback disease of the fish? Because it looks very much like a miniature saddle.

A mouth infection can also lead to the development of columnaris.

In case your fish dies from this, its mouth will appear bleached as if it were wearing lipstick.

When the infection inside the mouth persists, the columnaris eats away at the inner and outer surface of the skin resulting in flaking and swelling.

In terms of the identification of this condition, it is often misunderstood as a mouth fungus infection when it is actually columnaris.

In addition to taking a hold of the columnaris in the gills, this parasite can eat away on the inside of them, making them red and bloody.

Despite this, it is extremely difficult to detect columnaris of the gills when it is occurring within your tank water.

It is believed that most people only realize that their fish has died following columnaris of the gills.

The only way to determine the health of your fish is by looking for signs that point you in the direction of the gills.

With the gradual deterioration of the fish’s gills caused by columnaris, breathing becomes increasingly difficult.

Due to the increased effort necessary to breathe for your fish, its gills will move much faster than usual.

Even while your tank water is still, you may notice that your fish are swimming to the surface of the water at the surface of the tank water, where there is more oxygen.

Columnaris, which is a parasite found in fish, can cause them to lose a lot of energy, and also cause them not to eat well.

As a note, it is worthwhile to mention that lack of energy and refusal to eat are common symptoms of many diseases affecting aquarium fish which, on their own, do not necessarily indicate that your fish is suffering from columnaris.

Scratching is the ultimate proof that this fish is infected with Columnaris bacteria – this disease will cause your fish to itch.

Since your fish do not have had, they will swim closer to objects to rub against them to relieve the itching. As a result, this action can scratch and wear down its skin, muscles, and flesh.

After a few months, however, you may notice that the fins on your fish have faded, look ragged, or have been completely worn away, possibly as a result of the columnaris disease. Fin rot is the term commonly used to refer to this condition.

Columnaris does not cause fin rot in every fish. Generally speaking, it’s a secondary infection that is causing it, which brings me to my next point …

The fact that when your fish is infected with this disease it is certain that there is a high chance that your fish will get other diseases.

In addition to the stress and columnaris that have made your fish so weak, he is more likely to catch other diseases than if he wasn’t already weakened.

It is clear from the picture that this Platypus suffers from both Columnaris disease and itch

It is known as a secondary infection when a second disease is acquired after the first.

There occurs the possibility that one fish actually has multiple illnesses at the same time, such as battling two diseases simultaneously while you are trying to diagnose one. Because of this, diagnosing any fish disease can be difficult.

The columnaris disease can strike any aquarium fish, but certain fish have a greater tendency to contract the illness than others.

Those fish bred in huge numbers, with weak genetics, are a particular problem, such as betta fish produced in large numbers.

Columnaris is also a problem with livebearers that bear young, such as guppies, Endlers and platies.

What Are The Treatment Options For Columnaris?

Do you have a diagnosis of columnaris in your fish?

Do you have a diagnosis of columnaris in your fish?

So now that we know what the problem is, we need to get it cleaned up.

It is possible that if your columnaris are wrongly treated, the fish could even be harmed or worse.

Now those are completely opposed to the goals of our diving, aren’t they? Make sure you read through each step carefully before you take action!

Step 1: Quarantine

If any fish are exhibiting the symptoms of columnaris, you will want to put them into a separate hospital tank.

Several benefits can be gained from this:

One of the biggest advantages that a hospital tank can provide for a fish is that it will protect them from the infection of columnaris.

Secondly, it prevents the sick fish from being bullied by healthy tank mates, which could frustrate the healing process.

When a healthy fish is surrounded by a sick fish, they often drive it away instinctively to ensure their own safety.

Nevertheless, the sick fish in an aquarium will not be able to go anywhere, and this bullying will only stress them worse.

The dose of medication should then be adjusted according to how much alkaline water is available in your tank.

Having an aquarium as small as your hospital fish tank will reduce the amount of medication you need to stock it with.

The cost of medical treatment can increase substantially as a result of treating a 10-gallon system rather than a 30-gallon one using water.

Additionally, medication can affect healthy fish in a negative way. It is even possible to kill certain beneficial microorganisms in your filters if you take the right medications.

Therefore, when treating a harsh disease like columnaris, it is important to use only the most appropriate treatment. Only treating sick fish will reduce the impact of heavy medication on the rest of your swimming fish.

Step 2: You should check the quality of your water

Make sure that the water in your tank is as pristine as possible

You want to make sure that the water in your tank is as pristine as possible when you are fighting columnaris, just as you would in any other case.

It is advisable that you already tested the water in your aquarium on a regular basis with an aquarium test kit.

It’s a perfect opportunity to start now if you haven’t already done so.

Take a look at the following test kit and see if it is what you are looking for: pH, Ammonia, Nitrite, Nitrate, KH, GH

As well as making your fish recover faster by maintaining good water quality, it may also have an impact on how certain medications may affect your fish. 

Before advancing with the columnars treatment, if there are any out of the ordinary findings, you should fix them first.

Step 3: The heat needs to be turned down

Heat is the preferred mode of the columnaris. In a warmer environment, columnaris may spread more rapidly.

A temperature of no more than 75 degrees Fahrenheit (23.9 degrees Celsius) is ideal.

It is important to not let your water temperature exceed 75 degrees Fahrenheit because this will slow down the spread of columnaris disease and provide the best opportunity for survival for your fish.

If you want the water temperature to be lowered slowly, then you should make sure you do it slowly.

There is no doubt that fish are sensitive to sudden temperature changes. It is possible to kill your fish if you reduce the temperature too quickly. To learn more about aquarium temperature, please refer to our guide.

Generally, you want to make sure you maintain the water at the lowest temperature you can tolerate for your fish, rather than lowering it by 2 °F (1 °C) every hour until it reaches the desired temperature.

To make sure that your fish are still in their comfort zone when you are doing this, periodically test your aquarium’s temperature with a good aquarium thermometer.

The temperature should be adjusted to the lowest level they are able to tolerate as soon as possible and no lower.

You will need to study your fish’s body temperature to determine what is suitable for them.

If you own a community tank, which means that you have multiple types of fish in it, it is important you find that sweet spot where all the fish feel at ease.

Step 4: Make sure you take your columnaris medicine

Take columnaris medicine

There is a great deal of consensus among expert fish keepers about the best way to treat an outbreak of columnaris: nitrofurazone and kanamycin.

Personally, I also concur with this. On more than one occasion, I have successfully used this treatment to cure my fish of columnaris, and I have had great success every time.

This treatment as far as I am concerned gives your fish the greatest chance of surviving. The results seem to have been mixed when using one alone or the other – so using both together seems to have better results.

Firstly, you should get nitrofurazone medicine which has nitrofurazone as the active ingredient. I personally use this one…

It isn’t enough to use a medication containing kanamycin as the active ingredient. My personal preference is to use this medication.

Are you taking these two medications? You should now dose your fish to make sure they are healthy.

In order to achieve maximum effectiveness, here is how I dose them. After taking the first dose, follow this schedule as closely as possible. I would like to make sure that I take an extra dose of Furan-2 on day five as well.

Day 1: Furan-2 and KanaPlex

Day 2: Furan-2

Day 3: 25% water change, Furan-2 and KanaPlex

Day 4: Furan-2

Day 5: 25% water change, Furan-2 and KanaPlex

In cases of severe water pollution, you may need to give your fish back-to-back treatments for a total of 10 days if the situation is severe.

Based on the state of your fish after it has recovered, just you can decide if it is worth keeping.

Taking just these two powerful medications together should provide you with the long-lasting relief you need from columnaris.

Columnaris Can Be Prevented In What Ways?

Ways to prevent columnaris in cory catfish

It is generally believed that all aquariums contain a bacterium called columnaris.

I am therefore curious to know the reason why some fish do not become infected if this is the case?

The issue with columnaris is that it’s most likely to strike a stressed and weakfish – that is, a fish whose immune system cannot repel the disease on its own.

If you remove stress from your aquarium, then that would mean that your aquarium is made columnaris-proof, wouldn’t it?

I want to stress to you again that stress is the number one cause of fish death, in fact, you should stop being stressed out entirely.

It’s relatively easy to maintain your aquarium so that it doesn’t stress you out. Many of the things you need to do in order to successfully lead a successful life are actually things you should already be doing!

– Take care of your aquarium on a regular basis.

– You should quarantine new fish before you add them to your aquarium.

– Make sure you do not overstock the tank.

– Invertebrates and fish that are compatible with the ecosystem should also be stocked.

– You should test the quality of your water before you use it.

– Maintaining the parameters of water in a stable state.

– Clean and maintain your aquarium on a regular basis.

– Changing the water as needed.

– In addition to not overfeeding your fish, you should provide a balanced diet to your fish as well.

Doesn’t seem too difficult, does it? It doesn’t take much for you to maintain a happy, healthy, and disease-free aquarium full of fish.

You can take another step to prevent columnaris if you have hard water, which you can follow even if you don’t use hard water.

Your aquarium’s hardness should be reduced by decreasing the general hardness (GH).

A number of studies have shown that reducing the GH of your water impedes the development of columnaris infection in fish.

Simply put, in a less hard water environment, bacteria cannot attach themselves as effectively and can effectively deter them from attaching themselves to fish.


The columnaris disease is by far one of the most dreadful in aquariums as you can see from the image.

However, if you catch the fish early and treat it properly (and perhaps with a little bit of luck), it should be able to defeat the invasive columnaris fish.

Despite doing everything correctly, it is still possible that your betta fish won’t make it.

Perhaps you caught it too late, or maybe it’s a strain that will get out of your hands quickly.

You should not be too hard on yourself if your fish does not survive. We recommend going through our preventative steps at this time to ensure that the same thing does not happen to you again.

In addition, if treatment is not feasible, you might be forced to euthanize your fish if it is too late for treatment.

I know it can be difficult, but if you don’t, it might be the only option you have to save your fish’s life.

Video About Columnaris Cory Catfish

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