Wow are All Clownfish Born Male? Let’s Find Out!

4 min read

Clownfish, also known as anemonefish because of their infamous relationship with anemones, have other unique quirks to their personality.

For instance, I am often asked if all clownfish are born male.

All clownfish are born male. When there is a group or pair of clownfish, the dominant clownfish, usually the biggest one becomes female and usually pairs with the most dominant male. if a clownfish is kept alone they usually become female.

clownfish born male

Okay, I know this sounds crazy but let me explain.

How Does a Male Clownfish Become Female?

Let’s start at the beginning.

Even though all clownfish are born male, they are born with both male and female reproductive organs.

The development of the reproductive organs is governed by hormones.

Usually, the largest clownfish in a group becomes dominant for obvious reasons. If you have ever wrestled with someone bigger than you then you know the reason why.

When the clownfish becomes dominant, hormones trigger the female reproductive organs to fully develop. The scientific name for this is “protandrous hermaphroditism.”

Since the next most dominant fish in line is going to be her partner, his male reproductive organs fully develop.

Meanwhile, the rest of the group’s hormones are suppressed by the dominance established by the dominant pair keeping their reproductive organs from fully developing.

For the male that transforms into the female, his male reproductive organs are dissolved when he becomes a female.

The other clownfish practically remain juvenile from being suppressed by the dominant pair. They stay smaller and their reproductive organs don’t develop like those of the dominant pair.

This is the clownfish hierarchy, and it seems the juveniles are lying in wait to grow and develop if something happens to the dominant pair. They can remain juvenile for life if need be and develop as soon as one of the dominant clownfish passes away.

What Happens If The Female Clownfish Dies?

If the dominant female dies, then the male is already the second most dominant fish in the group so he becomes the most dominant, triggering the hormones that will develop his female organs and then dissolve his male reproductive organs.

If the female dies again, then the same process continues to happen to the last clownfish which leads us to our next question.

Can a Female Clownfish Turn Into a Male?

Becoming a female is at the top of the hierarchy for clownfish. Once they become a female, they can’t go back to being a male just as one of the adolescents who takes the place of the male. If the female dies he can’t go back to being an adolescent however he can become a female, and so on and so on.

Will a Lone Clownfish Become Female?

Okay, I hope you were paying attention because if a clownfish is by himself, he is still a male when he sets off on his own or is stranded. This is because there is no bullying or dominance from other clownfish to suppress his ‘I’m going to mature’ hormones.

So, you guessed it!

He is free to completely mature which culminates in becoming a female.

Scientific Explanation of Why All Clownfish Are Born Male

Mammals are born with chromosomes in their brain that result in certain hormones that determine their sex.

Clownfish are not born with these chromosomes.

The group of clownfish they are with determines the hormonal mix in their brain which then determines their sex based on the hierarchy described above.

Adolescent -> Male -> Female from the bottom up. However, this explains why when the female or male dies, then the hormones change in the next most dominant clownfish, based on the behavior around them.

Adolescent clownfish are doomed to forever be juveniles until the hormone mixture in their brain changes based on the hierarchy.

How Long Does it Take a Clownfish to Turn Female?

When a baby clownfish is born it can take about 3-4 weeks before it needs to find a host anemone if the clownfish even survive this long.

The clownfish has to find an anemone or it won’t survive much longer with so many predators around coral reefs.

Species of clownfish can smell or sense which type of anemone they can live with based on chemicals in the water.

Once they find an anemone the clownfish that already live there will chase the new clownfish off unless there is a spot in the hierarchy available.

Even then the new clownfish starts at the bottom of the hierarchy so there is no timetable as to how long it can take before it even gets a chance to become a female.

However, for the dominating couple, if the female dies it will only take 3-4 weeks for the next male in line to become a female.


I hope we thoroughly explained that all clownfish are born male, why, and how it works.

If you enjoyed our clownfish article, please check out our other articles on clownfish!

Clownfish Guide

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Pet Aquariums

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