Axolotl care

Do Axolotls Need a Filter for Their Aquarium?

Do Axolotls Need a Filter for Their Aquarium?

It's a question most axolotls have at some point.

Do axolotls really need a filter?

Will they live without one, or is it a death sentence?

Today's post is going to talk about just that.

We're going to look at the reasons people use filters, as well as address the results of not using one.

What is a Cycled Filter?

Let's talk about some differences between new filters and cycled filters for a minute.

When you get a brand new filter at the store, you are essentially buying something with potential to purify the water - not something that purifies the water (yet).

That's because it hasn't matured yet.

Maturing the filter requires running it on the aquarium for a period of time with a source of ammonia, such as fish food, live fish or liquid ammonia.

Basically, a new filter usually doesn't do squat for the water other than circulate and oxygenate it.

Which isn't a bad thing...

... But it can't clean the water until it has matured.

A matured filter is able to convert ammonia to nitrite, and finally nitrite to nitrate.

When the filter is able to do that it is considered to be "cycled."

This begs the question:

Do Axolotls Need a Cycled Filter to Purify Their Water?

Let me start off by saying:

It's not a black and white answer.

I will say this:

99% of people WILL want a cycled filter on their axolotl aquarium because it greatly reduces the workload at maintaining the aquarium.

Without something in the tank to remove ammonia that the axolotl is excreting, it continues to build up to dangerous levels.

High ammonia exposure to axolotls can result in serious injury or even death.

Even in small amounts, it can fry the gills, burning off their fluffy filaments.

That said:

There are several ways ammonia can be reduced.

Water changes are a big one.

What if I don't Have a Cycled Filter?

Ever heard of "tubbing" an axolotl?

When keeping an axolotl in a tub, those of you who have done this know the main benefit of tubbing is usually making large water changes easier than on a bigger tank.

So people will often tub their axolotl while their real tank is cycling.

To combat the ammonia problem in an uncycled tub, large daily water changes are performed.

These water changes remove the ammonia and keep the water safe.

And it can be much easier to do a 100% water change on a small plastic tub than a 100% water change on a 60 gallon tank, for example!


The long-term goal for the owner is usually to get the axolotl OUT of the tub so they can live in a cycled tank, which requires much less maintenance.

While there are many different types of filters, filters that employ biological filtration take care of the ammonia and nitrites, while the fishkeeper water changes to eliminate nitrates (which the biofilter does not generally remove).

As opposed to daily water changes needed for a tubbed axie, these water changes on a cycled aquarium often need to be performed only once a week or every two weeks, depending on the test results for nitrate and pH.

Another option is to put the axolotl in the aquarium and perform large frequent water changes for a period of time while the filter matures silently in the background.

This option can be quite a bit of work, but if you don't want to wait to add your axolotl to your aquarium and and don't have a cycled filter, it can work to keep them safe from water parameter problems.

Thoughts on Nitrates

As a result of performing 100% water changes on any tank or tub, unless your tap water has nitrates in it already, most likely you are going to get a negative nitrate test if you test the water.

Some people at this point will jump on that and say, "Hey, the tank isn't cycled because we have 0 nitrates! That means the water is unfit for the axolotl to live in!"

Not exactly.


Axolotls don't need nitrates.

Nitrate is ultimately a waste product, and it's actually better that those numbers stay lower, and 0 is perfectly safe for them.

The reason people worry about a 0 nitrate reading is because, yes, it usually means the tank isn't cycled.

(I say "usually" because that isn't always the case. But I'll come back to that in a minute.)


Usually if the tank isn't cycled, yes, there is a risk of ammonia/nitrite surges, also known as "new tank syndrome" to occur.


If the owner is performing large water changes on a regular basis, that prevents the ammonia and nitrite from surging, just like it prevents nitrates from showing up.

So it isn't always a bad thing and you don't always need nitrates for the water to be safe for the axolotl.

That said, most people do want to see nitrates on their test results as it means their biofilter has completed the nitrogen cycle and is correctly processing the ammonia and nitrites.

Let's come back to this nitrate question.

In some tanks that have been established for several months or even years, you may have 0 nitrates.

It's uncommon, but not unheard of.

Basically what is happening is while the biofilter is correctly processing the ammonia and nitrite and turning it into nitrate, there is denitrification occurring as a result of other biological processes in the aquarium.

Good news:

This is AWESOME for you as an axolotl owner, because it means you don't have to struggle like most of us performing regular water changes to bring the nitrate levels down.

Because, let's face it...

... That's what most of us ultimately have to do to keep our aquarium water in good shape for our lotl friends.

So there are two conclusions I would like to infer from the above:

  1. Don't assume 0 nitrates are harmful for your axolotl
  2. Don't assume 0 nitrates means the tank is uncycled. It may be, but isn't always the case.


I hope this article helped you to understand situations where a filter is beneficial and situations where there can be a workaround.

Thanks for reading!

Reading next

8 Axolotl Morphing Signs You Shouldn't Ignore

Leave a comment

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.