How to Tell the Difference Between Male and Female Axolotls

One of the most common questions axolotl owners ask is:

"Is my axolotl a boy or a girl?"

The answer is surprisingly simple once your axolotl reaches maturity.

The tricky part is that juvenile axolotls all look very similar, making sexing young axolotls little more than an educated guess.

Let's take a look at the easiest ways to tell the difference.

First Things First: Age Matters

Before trying to sex your axolotl, it's important to know that young axolotls haven't fully developed their adult characteristics.

Most axolotls become reliably sexable at:

• 12 to 18 months of age

• Around 18-20 cm (7-8 inches) or larger

Before this age, even experienced breeders can get it wrong.

That's why many younger axolotls are sold as:

Unsexed

or

Appears male/female

rather than being guaranteed.

The Easiest Way to Tell

Look Behind the Back Legs

The most reliable difference is the shape of the cloaca.

The cloaca is the vent located underneath the axolotl, between the hind legs and the tail.

Male Axolotls

What to Look For

✔ Large swollen cloaca

✔ Noticeable bulge behind the rear legs

✔ Slimmer overall body shape

✔ Longer appearance

Mature males often look leaner from above, with a very obvious swelling under the tail base.

Male Appearance

A mature male often looks like:

• Streamlined

• Athletic

• Slightly narrower through the body

The cloacal swelling is usually unmistakable once fully developed.

Female Axolotls

What to Look For

✔ Small, flat cloaca

✔ Wider body

✔ Rounder abdomen

✔ Broader appearance from above

Females often carry eggs, even when not actively breeding.

This naturally gives them a fuller shape.

Female Appearance

A mature female often looks:

• Chunkier

• Wider through the middle

• Rounder overall

Think "pear-shaped" compared to the male's more streamlined appearance.

Visual Comparison

Male

• Large cloacal bulge

• Narrow body

• Longer, lean appearance

  
  

Female

• Small cloaca

• Wider body

• Round abdomen

Why Do People Get It Wrong?

Several reasons:

Young Age

The most common cause.

Juveniles simply haven't developed their adult features yet.

Body Condition

A well-fed male may appear wider.

A slim female may appear narrower.

This can cause confusion if you're only looking at body shape.

Always check the cloaca first.

Genetics

Some bloodlines naturally produce:

• Large females

• Smaller males

• Intermediate body shapes

The cloaca remains the most reliable indicator.

Can Females Develop a Bulge?

Sometimes females can appear slightly swollen around the vent area.

However, it rarely approaches the size of a mature male's cloacal swelling.

If the bulge is obvious and clearly protruding, it's usually a male.

What About Breeding Behaviour?

Once mature:

Males Often

• Become more active during breeding periods

• Deposit spermatophores

• Display increased movement

Females Often

• Become noticeably rounder when carrying eggs

• Show interest in following males

However, behaviour alone should never be used to determine sex.

A Quick Test

Ask yourself:

Does the axolotl have a large, obvious bulge behind the back legs?

Yes?Likely male.

No?Possibly female.

Then look at overall body shape for confirmation.

The "Wait and See" Method

If your axolotl is:

• Under 12 months old

• Under 18 cm (7 inches)

the most accurate approach is simply patience.

Many axolotls that "look male" at six months become females later.

Many that "look female" suddenly develop male characteristics months later.

Nature likes surprises.

Little Lotls Tip

When purchasing younger axolotls, assume the sex is unknown unless the animal is fully mature and visually confirmed.

Any breeder guaranteeing the sex of a very young axolotl should be treated with caution.

At Little Lotls, mature axolotls are listed as:

✔ Visually Confirmed Male

✔ Appears Female

✔ Unsexed

to ensure buyers know exactly how confident the identification is.

Little Lotls Takeaway

Male Axolotls

✔ Large cloacal bulge

✔ Slimmer body

✔ Streamlined appearance

Female Axolotls

✔ Small cloaca

✔ Wider body

✔ Fuller abdomen

The older the axolotl, the easier it becomes to tell.

Until then, enjoy the mystery.

After all, axolotls seem to enjoy keeping secrets almost as much as Aristotle enjoys turning thermometers into sea monsters. 🦎💙