You just got your first axolotl, and now you want to know – is it a boy or a girl?

I remember asking this same question when I got my first axolotl back in 2017. The pet store told me it was a male, but honestly, they had no clue. The little guy was only 4 inches long and way too young to tell.

Here’s what I learned after keeping over 30 axolotls and breeding them for years: You can’t tell the gender until they grow up. And when I say grow up, I mean at least 8-12 months old.

Let me share everything I know about telling boys from girls, the mistakes I made, and how you can figure it out the right way.

Why You Need to Wait (And How Long)

Before we talk about how to tell the difference, you need to understand one thing: all young axolotls look like girls.

Yep, that’s right. When they’re babies, everyone looks female. There’s no magic trick to figure it out early.

When Can You Actually Tell?

Most axolotls show their true gender between 8 to 12 months old. Some boys show up earlier around 6 months, but it’s rare.

Here’s what I’ve seen:

• Boys usually show clear signs at 8-12 months
• Girls can take up to 18 months to confirm
• Size matters: they should be at least 6 inches long

I had a “female” turn into a male at 14 months. One day I looked, and boom there was the bump. It happens.

So if your axolotl is still small or young, just be patient. There’s no point stressing about it now.

The ONE Thing That Tells You For Sure

Okay, here’s the secret that works every time: look at the bump under the tail.

This area is called the cloaca. It’s where they poop and also where the breeding parts are.

What Boys Look Like

Male axolotls have a big swollen bump behind their back legs. This bump goes all around the area, not just one spot.

When you look from behind, you’ll see bulging on both sides. It sticks out pretty far from the body. You can’t miss it once you know what to look for.

The bump stays there all the time. It doesn’t go away.

What Girls Look Like

Female axolotls have a small bump that stays flat. It points down more than out.

There’s no side bulging. The area looks smooth compared to males.

But here’s where people get confused…

The “Poop Bump” Mistake

I made this mistake with my second axolotl. I thought she was a boy because I saw a big bump.

Turns out, she just needed to poop.

When females need to go to the bathroom, the area can swell up. It looks like a male bump for a few hours.

Here’s how to tell the difference:

• Poop bump: Points down in a V shape, goes away after they poop
• Male bump: Bulges to the sides, never goes away

Wait a day and check again. If the bump is gone, you have a girl. If it’s still there, you have a boy.

Other Ways to Tell Boys From Girls

The bump is the best way, but there are other clues too.

Body Shape

Boys are skinny and long. They look like hot dogs.

Girls are round and chunky. They look like potatoes.

This happens because girls carry eggs inside. Even when they’re not breeding, they look fatter.

But don’t rely only on this. Some boys eat a lot and look chubby too.

Tail Differences

Male tails are thick and long. They look strong and muscular.

Female tails are thin and short. They’re more delicate looking.

This one is harder to see unless you have both sexes to compare.

Toe Color Changes

When axolotls grow up, their toe tips change color. This happens to both boys and girls, so it doesn’t tell you the gender.

But it DOES tell you they’re getting old enough to check.

Light-colored axolotls (white, golden, pink ones): Toes turn black or dark Dark-colored axolotls (brown, black ones): Toes turn white or light

Once you see toe color changes, start checking for that bump.

Size Difference

Girls usually get bigger than boys. But this is the worst way to tell because it’s not reliable.

My biggest axolotl is actually a male. He’s 11 inches long. So size doesn’t always work.

What Their Behavior Tells You

Watching how your axolotl acts can give you hints, especially during breeding time.

Boy Behavior

Boys get super active during breeding season (spring and fall). They do this weird dance thing where they wiggle their tail really fast.

They also:

• Chase other axolotls around
• Bump into the female’s back end
• Leave little white cone things in the tank (these are sperm packets)
• Get more aggressive with other males

One time I watched my male do the tail dance for 3 hours straight. It was exhausting just watching him.

Girl Behavior

Girls are much calmer. They don’t do the crazy dance.

When a girl is ready to lay eggs, she:

• Swims around like she’s looking for something
• Climbs on plants and decorations
• Acts restless and doesn’t sit still

Then you wake up one morning and there are hundreds of eggs everywhere. That’s how you KNOW you have a girl.

Mistakes I Made (So You Don’t Have To)

Let me tell you about the dumb things I did when I started.

Mistake 1: I checked the gender too early. My axolotl was only 5 months old. Everything looked female because they ALL look female at that age.

Mistake 2: I thought my girl was a boy because of a poop bump. I even bought a new tank to separate “him.” Then the bump disappeared the next day. Oops.

Mistake 3: I trusted the pet store. They labeled my axolotl as female. Turned out to be male. Pet stores just guess because young axolotls can’t be sexed.

Mistake 4: I only looked at body shape. My chunky boy looked like a girl until I checked the cloaca area properly.

Mistake 5: I didn’t wait until 18 months to be 100% sure. What I thought was a female at 10 months turned out male at 15 months.

Why Knowing the Gender Actually Matters

You might think, “Who cares if it’s a boy or girl?” But it matters more than you think.

Stopping Surprise Babies

If you have two axolotls and they’re opposite sexes, you’ll get eggs. Lots of them. Like 500-1000 eggs.

Most people aren’t ready for that many babies. Trust me, I learned this the hard way.

Keeping Everyone Happy

Boys can stress out girls by constantly trying to breed. Girls can get tired and weak from laying eggs too often.

If you know who’s who, you can give everyone their own space.

Breeding Safely

If you DO want baby axolotls, you need to wait until they’re old enough. Girls should be at least 18 months old before breeding.

Breeding too young can hurt them bad. It stunts their growth and they might not live as long.

Health Problems

Some health issues only happen to one gender:

• Girls can get egg-bound (eggs stuck inside)
• Boys can get cloaca problems from swelling

Knowing the gender helps you spot problems early.

What If You Still Can’t Tell?

Sometimes it’s just hard to figure out. Here’s what to do:

Wait Longer: If your axolotl is under 12 months, just give it time. Check every few weeks.

Take Pictures: Get clear photos from behind and from the side. Then post them in axolotl groups on Reddit or Facebook. Other keepers can help you.

Watch for Breeding: If you have multiple axolotls, just wait and see what happens during breeding season. The boys will do their dance and girls will lay eggs. That’s proof.

Ask a Breeder: Find someone who breeds axolotls and send them pictures. They’ve seen hundreds and can tell right away.

Pick a Neutral Name: Can’t decide? Choose a name that works for both. Problem solved.

Can Axolotls Change Gender?

No. Once they’re born as male or female, that’s it for life.

Some fish can change from male to female or back. Axolotls can’t do that.

So once you figure it out, it won’t change later.

Quick Cheat Sheet: Boy vs Girl

Here’s a simple table to remember:

What to Check	Boy	Girl
Bump area	Big and swollen, bulges sideways	Small and flat, points down
Body shape	Long and slim	Round and chunky
Tail	Thick and long	Thin and short
Behavior	Active, does dance, chases others	Calm, lays eggs
Age when clear	8-12 months	Up to 18 months

My Best Advice After 8 Years

I’ve kept axolotls since 2017. I’ve had babies, adults, and everything in between.

Here’s what I want you to remember:

Don’t rush it. Young axolotls all look the same. You can’t force it.

The bump is everything. Forget body shape, tail length, and size. Just look at the cloaca area. That’s your answer.

Check after they poop. Don’t mistake a temporary poop bump for a male.

Wait until 18 months for girls. Boys show up early, but girls take longer to confirm.

It’s okay not to know. Your axolotl doesn’t care what you call it. They just want food and clean water.

Honestly, unless you’re planning to breed them or you have multiple axolotls living together, the gender doesn’t matter much for daily care.

Both boys and girls need the same water temperature (60-64°F), the same food (worms, pellets), and the same tank setup.

So relax, enjoy your axolotl, and let nature reveal the answer when it’s ready.

What To Do Next

Now that you know how to check, here’s your action plan:

Step 1: Check how old your axolotl is. Under 8 months? Stop worrying and wait.

Step 2: Look for toe color changes. That means they’re growing up.

Step 3: Check the bump area behind the back legs. Big bulge = boy. Small flat bump = girl.

Step 4: Still not sure? Wait another month and check again.

Step 5: Take photos and ask experienced keepers in online groups.

That’s it. It’s not complicated once they’re old enough.

Questions People Always Ask

Q: My axolotl is 6 months old. Can I tell the gender now?

Maybe, but probably not. Most aren’t clear until 8-12 months. You might have to wait longer.

Q: The pet store said mine is female. Is that true?

If your axolotl is young, the pet store is just guessing. They can’t actually tell with babies.

Q: Can girls have a bump too?

Yes, but only when they need to poop. It goes away after. Male bumps stay forever.

Q: My axolotl looks female at 10 months. Is it definitely a girl?

Not yet. Some males don’t show the bump until 12-15 months. Wait until 18 months to be certain.

Q: Does gender affect how long they live?

Not really. Both boys and girls can live 10-15 years with good care. But girls who breed too young might have shorter lives.

Q: Can I keep a boy and girl together?

You can, but they WILL breed. You’ll get hundreds of eggs twice a year. Only do this if you want babies.

Q: My axolotl laid eggs. So it’s female, right?

Yes! That’s 100% proof. Males can’t lay eggs.

Final Thoughts

Finding out if your axolotl is a boy or girl takes patience. You can’t rush it.

I remember spending hours staring at my first axolotl, trying to figure it out. Looking back, I wasted so much time.

The truth is simple: wait until they’re grown, check the bump, and you’ll know.

Everything else body shape, tail size, behavior those are just bonus clues.

The bump tells you everything.

So save yourself the stress. Wait it out. Your axolotl will show you the answer when it’s time.

And remember, whether you have a boy or a girl, you’ve got one of the coolest pets on the planet. These little water dragons are special no matter what.

Got questions about your axolotl? Drop them in the comments below. I read every single one and I love helping other axolotl keepers.

Now go check that bump and let me know what you find!