I get this question a lot:
"Is my axolotl a boy or a girl?"
"How do you even tell?"
What Age does the Axolotl Need to Be?
Axolotls need time to reach sexual maturity.
Up until that point, when they are pretty young, it's literally impossible to tell, so it's basically a 50/50 guess.
So when you are looking at a juvenile 3 or 5 inch lotl wondering what it is, your guess is as good as mine.
This can make it frustrating in a way for people who want to name their axolotl... unless they decide to just go with a gender neutral name.
So, the bottom line?
Before you can tell your axolotl's gender, they need to be old enough.
It usually isn't until the 8-12 month mark that you can know.
In some cases, males can take up to 18 months to reveal their true identity to you as the owner.
This is more of the exception than the norm though, and they can be sexed earlier than 9 months in some cases too.
Again, more of an exception than the rule.
Usually when the axolotl reaches around 8" it is at or close to being sexually mature.
Males tend to mature earlier than females, and some can be distinguished even at only 6" long.
Methods to Sex Your Axolotl
Once axolotls are sexually mature, it is pretty straightforward to tell the difference.
Before we get started...
A quick disclaimer:
Not all of these methods are 100% reliable.
I have tried to give all the known ways to distinguish the gender of your axolotl in the methods below.
At certain times during the course of the axolotl's life, it is easier to tell then at other times.
But hopefully this points you in the right direction!
1. Examine the Cloaca Area
The most reliable method of sexing your axolotl (just by looking at them anyway) is to check the area behind their back legs, called the cloaca.
In females, the cloaca is more flat against the silhouette of the body with no significant bulge on the sides of the tail.
It is also relatively short and not really noticeable.
There can be something called a "poop bump" females get which makes it get a little bigger than normal.
The poop bump generally makes the area sag down more in a pointed "V" or softer "U" shape rather than bulge out to the sides.
Once you've compared it to the male's cloaca, you can see the difference.
And the other way to tell that it is a poop bump is when the area returns to normal and flat after the axolotl goes to the bathroom.
In males, once the male axolotl reaches sexual maturity, it will get a bulge behind its back legs.
This bulge may vary in size from axolotl to axolotl, but it will still be distinct.
Some males are more "obvious" than others.
You can see it more from above too.
The cloaca area also becomes longer for males than for the females.
During breeding time, the bulge often becomes much more prominent and flushed.
2. View the Body Shape from Above
In general, females have a rounder body shape from carrying eggs.
They are usually wider towards their abdomen and the further down you look.
This "pear shape" look arises from carrying the eggs.
Periodically, a female axolotl produces eggs, then reabsorbs them if no male spawns with her.
Her shape generally stays more rounded than the males though, regardless of which stage she is at with her eggs.
Males from above are leaner...
They then have (added to their overhead profile) that bulge I talked about in the last point, which can be seen from above, at the base of their tail.
3. Check for Toe Tips
When axolotls get more mature, they develop toe tips, almost like claws.
On white axolotls like leucistics, the toe tips are black.
On black and dark axolotls like mels and wilds, the toe tips are white.
There is some debate about whether or not this indicates sexual maturity.
4. Witness Breeding
Obviously the most 100% accurate way to tell the gender of an axolotl is to witness the unusual breeding event.
Males wiggle their tales and race around the tank laying sperm cones.
The female follows behind with her nose against his cloaca, possibly trying to investigate what is going on.
The male then pushes the female around to get her to land on top of the sperm cone and absorb it into her body.
The very distinct behavior between the sexes during this occurrence will give you a reliable answer.
Not long after this happens, the female axolotl deposits her eggs in a time consuming process.
So if you see an axolotl laying its eggs all over the place, you know it is a female beyond a shadow of a doubt :)
5. Compare Sizes
This is not the most reliable method, but female axolotls tend to be bigger and attain a greater length than males.
A lot of this does come down to genetics though.
You can have many other factors besides gender, such as genes, that cause the axolotl to get quite large, even males.
This was touched on in the post about how big an axolotl can get.
But even if they are the same length, add to it how the males look relatively scrawny next to the female and it does add to the impression that the female is larger than the male.
Figuring out the gender of your axolotl may take some patience and some research, but it can be very useful when it comes to housing and breeding these fascinating animals.
Hopefully this article helped to point you in the right direction.
Thanks for reading!