Is Mold Bad For Reptiles?

is mold bad for reptiles

Reptiles are so different from us in many ways.  But in other ways, they are still very similar to us.  For example, humans and reptiles both have lungs and use them to breathe.  Thinking about your pet like this might help you understand that many of the things that are bad for our health can also be bad for our pets’ health.  Mold is something you might notice from time to tie in your reptile’s tank.  Is this something to worry about?

Is mold bad for reptiles?

The short answer is, yes.  Mold can be harmful to reptiles in the same way it is harmful to people.  Mold can cause respiratory and skin disease and in most cases should be removed and cleaned immediately.  If there is mold in your house somewhere, this can also cause issues for your scaly friends.  

In almost all circumstances, mold is bad for you and your pets.  But, there is one exception that we will discuss below.

What Is Mold?

To understand why mold can be harmful to reptiles, let’s talk a little bit about what mold is!

According to the CDC, mold is a type of fungus that grows on damp and decaying things.  Mold can grow on old food, dead plants, and even dead animals.  In your reptile’s enclosure, you might find mold growing on sticks, substrate, or old food that died and was never eaten.

Indoors, mold is mostly seen in places that are too damp.  One of the dangerous things about mold is the way that it spreads and grows.  Mold grows by releasing tiny spores into the air which is one of the reasons why it can make you sick.

To make things worse, some molds are even toxic and can cause serious health issues!

How Can Mold Make Your Reptile Sick?

So, how can mold make you and your pets sick?

Even if your leopard gecko or bearded dragon isn’t eating the mold, just being in the same room as it can make them sick.  Whether that mold is in their tank or in your house, it could be causing serious health issues.  This goes back to the spores that mold reproduces with.  Unfortunately, those spores are so tiny that if they are ingested, can start to grow and harm tissues inside of the body, especially the lungs which are quite sensitive on most reptiles.  Most sicknesses caused by mold involve difficulties breathing.


Aspergillosis is an illness caused by a specific type of mold.  This mold is commonly found on old leaves, old food, and especially old grains.  Birds and reptiles are super sensitive to this type of mold and are prone to developing aspergillosis.  Some symptoms of Aspergillosis include coughing, wheezing, and fever.

If you are concerned that your pet reptile has aspergillosis, you should take them to see a veterinarian ASAP.  Luckily, it can be easily treated with anti-fungal medication.

Is It Ever Okay To Leave Mold In A Reptile Tank?

At this point, we’re clear that mold is bad for reptiles.

Their lungs and tissues are just as sensitive (maybe more sensitive) to the pesky mold spores.  As a rule of thumb, if you see mold in your house you should try and clean it.  The same goes for your reptile’s tank.  It’s a bad idea to let the mold sit in a tank, in a controlled environment mold can grow quickly and make your pet sick.  If you have a normal setup, where your reptile is the only living creature, mold is never okay.

However, the one exception to this rule would be in a bioactive terrarium.

Bioactive Tanks

Bioactive tanks are miniature ecosystems that, at their best, maintain and lean themselves.  Bioactive tanks have living plants, rich soil, and even special bugs called springtails that are supposed to help control fungus levels.  If you see a small amount of mold in your reptile’s bioactive tank, this could actually be a good sign.

Mold is a signal that your bioactive environment is working, and that things like feces are being decomposed by the tank itself.  Unfortunately in such a small space, mold could still make your pet reptile sick.  Out of caution, I would recommend removing mold even from bioactive tanks, but I suggest doing your research and deciding what is best for your unique environment and pet.

How To Clean Mold From A Reptile Tank.

If there is mold in one area of your reptile tank, it’s probably everywhere!  Mold is bad for snakes, lizards, turtles, and for you!

The most effective way to clean mold is to deep clean your reptile’s entire tank.  This means you will want to put your reptile in a temporary enclosure and empty everything out of its tank.  You’ll want to remove all of the substrate and replace it with a new substrate.  Any furniture or features in your reptile’s tank will need to be removed and disinfected.  Then, you’ll want to clean and disinfect all the surfaces of your reptile’s tank.

As you clean, make sure you keep your retile’s dishes separate from your human dishes!  Because reptiles all carry and shed salmonella, you shouldn’t put any of your reptile’s hides in your family dishwasher.  You can read more about salmonella and why you shouldn’t share dishes with your reptile here.   To clean you can use dawn soap, and to disinfect you can use a variety of solutions.  You can try using solutions that are specially made for reptiles or you can make your own hydrogen peroxide solution.

This video shows how a large-scale reptile facility cleans and disinfects its enclosures to keep its reptiles happy and healthy.

Once you’ve thoroughly cleaned and disinfected your terrarium, you can put your pet reptile back in and let them enjoy the fresh air!

How To Keep Mold Out Of Your Terrarium

The easiest way to keep your terrarium mold-free is to prevent mold from growing in the first place.

The most likely cause of mold growth in your terrarium is probably an imbalance of humidity.  Figuring out the perfect relative humidity for your reptiles can be difficult.  Once you know the number, it’s a game of small adjustments until you finally get it right.  Even then, a change in seasons can cause humidity to rise and can cause mold to grow.

Reducing Humidity In Your Reptile’s Terrarium

If you’re not sure how to reduce humidity in your reptile’s terrarium, here are a few quick tips.

To reduce humidity in your terrarium, you can increase ventilation and decrease the amount of standing water.  You can also try using a specialized substrate that doesn’t hold moisture.  In a pinch, you can even throw in a rice-filled sock that will help absorb extra moisture.  For a more detailed list of ways to lower humidity, read our article about it here.  And don’t worry, if your humidity drops too low for your reptile, there are many ways to get the moisture back into their environment.

Keep The Environment Clean

In addition to keeping humidity levels balanced and low, you should also keep your reptile’s tanking clean!

Leaving dead crickets in your enclosure is not necessarily a bad thing, but letting them sit and rot is.  You should also remove any other food that your reptile doesn’t eat.

Mold needs something dead or decaying to grow on.  So if you make sure to remove all feces, food, and dead plants right away, you can keep mold at bay.

Final Thoughts

Mold is bad for your entire family’s health, including your pet’s.  Even though reptiles are very different from us, they can still get sick from mold exposure in the same way we can.

If you do see mold in your pet’s enclosure, clean it right away.  Keeping humidity levels balanced and cleaning out old food will help keep mold from growing in the first place.  Mold in a bioactive tank should still be approached with caution and the health and safety of your reptile should always come first!