Axolotl care

Axolotl Fungus Prevention & Treatment

Axolotl Fungus Prevention & Treatment

Fungal infections in axolotls (saprolegnia, columnaris) are relatively common in axolotl tanks.


It is a disease that likes cooler water more than warm water.

And we keep our axolotls cool for their health.

Plus, the setup of most axolotl tanks lends to the growth of fungus as most are usually bare bottom or sand only.

The good news is in most cases they are entirely preventable as well as treatable.

Appearance & Diagnosis

Fungus typically appears to the naked eye as fluffy, cotton-like tufts on the exterior of the axolotl's body, usually the gills or on the site of a wound.

Gill fungus can also result in whitening, cloudy tips of the gill stalks and degeneration of the gill filaments, which is tissue necrosis.

Under a microscope, the infection looks far different.

When inspecting the white fluffy matter under a microscope, the appearance often resembles long "branches" protruding from a central mass (this is saprolegnia).

Columnaris is actually not a fungus, but a bacteria, though it appears to the naked eye like a fungus (source).

A microscope is the only way to tell the difference.

If the fungus is attacking the gills, the filaments often show signs of erosion, degeneration and white patches.

Sometimes a fluffy mass will lodge within or on the tip of the gills.

On the skin, it may appear as a ball or slimy, cloudy area.

The legs and hands/feet are a common site of fungal attack.

Left untreated, fungus can be lethal to the animal - and in a short timeframe.

The other sad thing about fungus is it can devastate the beautiful frills on your axolotl's gills, leaving them with nothing but bare stalks.

Causes of Fungus

Fungus commonly occurs on the site of an injury or abrasion, such as a bite by another axolotl, in which case it would be a secondary infection.

Fungus can also attack the gills of the axolotl (very common) or skin.

Poor water quality or improper water parameters can lead to a simultaneous weakening of the axolotl's immune system and/or caustic abrasions that lead to secondary infection.

Sometimes an animal may get fungus and we aren't exactly sure why, but it likely has to do with stress or something being off in their environment (source).

An unbalanced environment with too much dissolved organics may lead to outbreaks of fungus...

... Or lack of a strong microbiome.

This is common in tanks that do not employ enough water changes or nutrient recycling.

Fungus is a persistent disease and can frustrate many axolotl owners who feel like they've "tried everything" and it just keeps coming back.


There are many options available for treating fungus, including salt baths, antiseptics or antibiotics.

Salt baths or tea baths are a popular option that may be effective for some.


Besides being stressful to the axolotl, the fungus often comes right back in a matter of days even after repeated baths.


I also prefer to avoid stronger chemicals unless it is truly needed.

For very, very light fungus issues, IAL (Indian Almond Leaves) may be sufficient.

They aren't very strong though, and fungus can be quite aggressive to treat.

Another issue?

Many common medications for fungus in fish tanks are unsafe for axolotls.

Another danger you can run into is if the "fungus" is actually not fungus, but Columnaris.

Unless you have access to a microscope, it is a good idea to use something that can treat BOTH in one shot.

Otherwise you can find your treatment is not working.

This is important:

Please do not try to pull the fungus off the axolotl manually.

Besides being stressful to the animal, this causes pain to the axolotl as their gill filaments are sensitive and it usually does not get all the fungus anyway, causing it to return.


With whatever treatment you choose, please note that it can take 1-2 weeks for the fungus to resolve, if it has been more than that you may need to change treatment.

My Preferred Treatment

One of my customers had her axolotl develop some fungus and reached out for help.

These were the photos she shared with me (before):

(You can clearly see a white "ball" of fungus behind the gill stalks.)

At my first recommendation she tried a salt bath which helped quite a bit initially, but the fungus simply returned later.

I gave her my other treatment protocol, which she followed.

This was her axolotl after the treatment:

Of course, she was very happy at the recovery her cutie made...

"He looks great! His frills are much, much larger than I was expecting! He looks so goofy but it just adds to his already high cuteness levels! But the fungus is gone, and I am so thankful!"

I developed this treatment protocol based on the medication widely used for external bacterial and fungal infections in ornamental fish.

It has worked extremely well for my lotls and others I have recommended it to.

So well that I decided to make it available to other axolotl owners.

The secret?

I named it "Axie Aid."

This medicine has been tested extensively here at Fantaxies and has been found to be both safe and effective for hundreds of axolotls.

We even use it on the animals within our own prized breeding colony, we trust it so much.

It is available for purchase on our website.

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In general, isolating the infected animal is a good idea to prevent the spread of fungus and allow them to recover in peace.

Unless, of course, you have a widespread problem in your tank.

While they are in the hospital, I like to perform large daily water changes to keep the water super clean.

Other Treatments

If the medicine is not available where you live, there are some other treatment options, though they are not my go-to generally speaking.

1. MinnFinn

Another treatment I use for fungus (including Columnaris) in axolotls is something called MinnFinn, which is an oxidizing agent.

It can be used at regular strength for the 1 hour bath and repeat 1-3 times, depending on the case.


In harder water, it doesn't work as well at regular strength.

Or in water that has been treated with Prime.

Generally by the next day the fungus is totally gone, but it depends on the severity of the case and may take a week or two to fully clear.

In severe cases, treatments may need to be administered up to 5 times.

It is very gentle and effective at the same time.

It can even be used on babies as small as an inch without harm.

2. Salt

Longer-term bath treatments can also be useful.

I.e. semi brackish water.

You can try Himalayan pink salt in the water, at a ratio of 3TB per 5 gallons, which is similar to Holtfreter's solution.

Salt can be used in conjunction with the every other day MinnFinn baths.

3. Microbe-Lift Artemiss

Another treatment I have found works in some situations for axolotls is Microbe-Lift Artemiss.

It does not cause any harm to the lotls and is formulated with essential oils.

It can be used in conjunction with salt and Indian Almond Leaves.

It is also good for bacterial issues as well.


My personal testing has found it is not effective for most cases of fungus.

4. Peroxide swabs

In some cases, an axolotl may get fungus so bad that most if not all the gills are affected and it can get pretty serious.

In this case it may be necessary to resort to the more drastic treatment of hydrogen peroxide swabs.

Generally I like to avoid this as it's really stressful on the animal.

The fungus also tends to return.

To do this:

  1. Get brown bottle peroxide, which is 3%, then dip a Q-tip in it and set by.
  2. Holding the axolotl out of the water in one hand, use the other hand to quickly and gently swab the affected areas on the gills once.
  3. Leave the axolotl out of the water for approximately 5 seconds.
  4. Return the axie to the water. The gills where it was touched will bubble and fizz and may appear cloudy, but it will go away shortly.

By day 2 the axie should look much better. If not you can repeat.


This method can burn the axolotl's gill filaments if it is applied too long.

Honestly it's better to use the MinnFinn if you want something gentler but as effective as peroxide.

5. Methylene blue

Methylene blue is a powerful dye.

I personally have not used this, but it is said to be effective for treating fungus on eggs and on the axolotl's body and gills.

It is harmful to the tank's beneficial bacteria, so it is recommended to use it only in a hospital tank instead.

It can be useful for treating aggressive fungus infections.

Side note:

Meth blue is useful to keep around as an emergency treatment in case your axolotl ever jumps out of the tank (it enhances oxygen uptake which can save a partially dehydrated lotl).


Preventing fungus is much simpler than having to treat it.

Obviously the best way is avoiding what causes fungus, like injuries or poor water quality.

But what if you still struggle with fungus even so?

One may think that raising the temperature is an easy solution, but that would make the water unsuitable for the animal to live in as well.

There are several approaches.

Some people keep Indian almond leaves in their water as a preventative, and I don't discredit it one bit.

I personally am not as fond of them because the tannins darken the water and bring down the pH, unless you remedy this by adding some buffer as well.

(Axolotls like hard water.)

That said, I do use them occasionally, just not in my display tanks.

Oak leaves or alder cones may help to some degree as well and be available locally (for free).

Again, these can bring down the pH.

There is also a concoction that can be created at home called Holtfreters solution which has been shown to be an effective treatment in preventing fungus.

I am not opposed to this, but for me...

I like to keep it simple.

The recipe may be effective but it is too involved for my simple methods of fishkeeping.

Trying to monitor the salinity levels and mixing multiple ingredients is tedious.

So what do I do?

1. Consider the Environment

Fungus is usually brought on by unfavorable environmental conditions for the axolotl.

Problems with the biome in the tank are a theory worth considering.

Most axolotl tanks are generally kept bare bottom or a thin layer of sand.

They rarely have live plants, or if they do, it is rarer still that they are actually flourishing.

This might make it pretty easy to vacuum away every speck of crud and make decorating easy, but it doesn't afford a strong place for good microorganisms to flourish.

A tip?

Consider a more natural approach that is conducive to a strong colony of good tank flora.

This helps to out-compete the bad organisms such as those that cause fungus.

A planted tank with a Walstad-style substrate is highly favorable to keeping your aquarium's ecology in balance.

When the plants are thriving, they too provide good homes for the growth of beneficial bacteria that outcompete the bad ones (not the same as the ones in your filter).

Many aquarists notice problems with fungus attacking their animals to subside for good once they make the switch.

2. Salt

In the past this was something I would use as a preventative, one of which is himalayan pink salt.

The benefits are numerous:

  • Buffers the TDS of the water
  • Replenishes trace minerals
  • Inhibits bad bacteria growth
  • Inhibits some fungus
  • Inhibits harmful effect of nitrite

There is no standard measurement for the dosage as I go by the TDS of the water out of the tap and the final value, which varies greatly depending on your state.

For states with softer water, you need more, harder water needs less.

I mix enough in gradually 1/4 tsp at a time to bring the TDS to between 250-300. I use a TDS reader to check the value continually until it is where I want.

I like to use the fine grain kind because it dissolves very quickly.

Some people may object to adding salt to the water because of the stress in fluctuating parameters during a water change (salinity is a parameter).

This is a legitimate concern.

But I do two things to overcome this:

  1. I rely on good filtration + smaller water changes to keep my water in good shape more than lots of big water changes
  2. When I do water changes I use another container (such as a bucket) to dissolve my himalayan pink salt in first and bring the water to the proper TDS

This is what I have found works very well for me and my own personal methods.

There are other methods out there that may work better for you!

That is my tip for you to help prevent fungus :)

3. UV Sterilization

Aquariums in most homes receive little if any direct sunlight, and even if they do get some most windows are designed to block out UV light rays.

In the wild, it is a far different story.

The sun rays penetrates the water, helping to perform UV sterilization.

For us?

This is where the UV sterilizer can come in handy.

UV rays are an effective way to destroy fungus in the water (source).

This helps to keep waterborne pathogen levels low and decrease the risk of fungal outbreaks.

I highly recommend UV sterilizers for axolotl owners as a preventative approach for this disease.

Just take care that you don't create too much current with it.

4. Clean Water

Performing regular water changes is an important way to keep the dissolved organic levels in the water to a minimum.

These dissolved organics can contribute to fungal outbreaks when nutrient recycling is not properly implemented.

This includes uneaten rotting food, a major cause of fungus.

It does not harm the axolotl to perform even up to a 100% daily water change, provided the parameters and temperature of the new water are close enough and it is properly treated.

Daily vacuuming can be tiresome but in tanks that are not the el natural style, it can be invaluable.


Beating fungus can be done, when caught in time.

It is also a preventable disease in axolotls.

I hope this article has helped you, thank you for reading.

Reading next

Gravel for Axolotls: What Nobody Tells You
3 Tips on How to Keep an Axolotl Tank Cool this Summer

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