Axolotl care

How Big Do Axolotls Get? Full Grown Size & Length

How Big Do Axolotls Get? Full Grown Size & Length

It's true:

Axolotls may start out SUPER tiny.

And they don't stay that way ;)

But how big can they actually get?

In this post we're going to look at the possible range of sizes...

... As well as several factors that play a role as well.

So let's get into it!

How Big do Axolotls Grow?

There is quite a bit of variety when it comes to full grown axolotl size.

Much of this depends on the individual.

That said:

The average size for an adult axolotl is approximately around 8", though some may not reach that full size (or exceed it) for a variety of reasons.

On the larger end, an axolotl can reach up to 15 inches.

(The biggest axolotl attained a whopping 18" in length.)

On the smaller end, they may only get 6 inches, or not even that, especially if they have a genetic condition (more on that later).

Some axolotls that are larger than normal are sometimes referred to as "giants."

6-10 inches is the general range for final growth.

It usually takes between 18-24 months for an axolotl to reach its full size potential.

Factors that Influence Axolotl Growth

1. Genetics

Genetics are a major contributing factor when it comes to how large or small an axolotl will get.

Some conditions can have a genetic cause.

There are two common conditions that can cause an axolotl to remain much smaller than normal for the span of its entire life.

The first is dwarfism.

A dwarf axolotl is identified by:

  • A head that is the same size as its siblings, but a body that is much shorter than it normally would be
  • They display a rounder body with a classic wavy tail
  • Dwarfs may have shorter limbs than normal, albeit with regular length digits

Dwarfs are primarily thought to be a genetic anomaly, though there is some line of thinking that nutrition and water quality may also result in dwarfs.

It is argued that with proper care, dwarfs can live a long, normal life as any other axolotl.

The second condition that can be genetically caused is "minis."

Minis differ from dwarfs in that their proportions are those of a normal adult axolotl, but they never attain the full size.

A rule of thumb offered for determining if an axolotl is a mini is that if it has not reached more than 6" by the time it reaches is a full year of age, it is a mini and not a regular axolotl.

Minis stay 6" or under their entire lives and are not known to incur any health issues from being smaller than normal.

To tell whether a smaller than normal axolotl is a dwarf or a mini takes time, as when they are littler the differences are not as apparent.

What causes a mini?

While other causes result in a mini (such as nutritional deficiency or water quality issues), genetic predisposition is a big one.

Dwarfs and minis both may require to be housed separately to avoid being picked on by the other larger axolotls.


Some axolotls are not minis or dwarfs, but just slower growers, most likely due to not getting the food as fast.

These eventually catch up to the rest in size, they just take a while.


Short toes syndrome (referred to in the past as disproportionate dwarfism) is a deadly genetic disease that causes an axolotl to suffer from excess fluid in the body, stumpy limbs with blunt fingers and toes, and eventual organ failure (observable by the animal swelling up with bloat) - resulting in the animal's death.

This condition happens when the gene that is responsive for their regenerative abilities ceases to function properly.

These animals are not true dwarfs at all, though their appearance is similar (some even showing the same wavy tail).

And sadly they do not live very long even with the best of care, most not surviving past 2 years.

Like dwarfs, animals with this condition should never be bred.

Giantism in axolotls has a genetic connection as well, and some axolotls turn into monsters despite receiving average care.

2. Feeding & Nutrition

How often the axolotl is fed can play a large role in final size.

Smaller, more frequent feedings tend to push faster growth.

How much the axolotl is fed at a time is also a key role, with smaller portions not given as often tending to promote slower growth.

Some types of food tend to stronger growth than others.

A highly nutritious diet helps to promote good growth as well, with live foods seeming to provide the best results.

For example:

Foods that are particularly high in digestible protein, such as most worms (i.e. blackworms, bloodworms and earthworms) are known to help push growth in young and maturing axolotls.

Live foods are particularly beneficial as they have added nutrition.

Exactly what the axolotl is eating can contribute to better or less impressive growth.

Axolotls that are fed more frequently and allowed more space to grow tend to reach sexual maturity faster than otherwise.

How Fast do Axolotls Grow?

Fun fact:

For the first 6-8 months of their lives, an axolotl generally grows approximately 1" per month.

(This is assuming the animal is well fed with nutritious foods, as well as provided adequate space and water quality.)

After that, their growth starts to slow down significantly.

Some factors can slow down the growth rates, including difficulty accessing food due to competition or physical limitations.

And, of course, a genetic factor that would result in a slower growth rate.

Likewise, some can grow much faster due to genetics, or being allowed more in terms of food.

Temperature can also play a role in growth rate.

There is one line of thinking that temperatures on the warmer end of their tolerated temperature spectrum can play a role in promoting faster growth.

Keep in mind that neither food nor warmer water should be overdone as overfeeding and overheating can cause harm to the animal.

Wrapping it All Up

How big an axolotl will finally get can be somewhat of a mystery...

... But knowing factors like comparative growth rate to other siblings, nutrition, tank space and lack or presence of genetic conditions can help you to guess how large your axolotl will get.

Thanks for reading!

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