The Weird Yet Fascinating Gender Determination Process In Clownfish

Perhaps clownfish get their comical name because they look as though they’re painted like a clown’s face, or maybe it’s for some other reason. We don’t precisely know why they’re named that, but there are many other interesting things about clownfish that many people don’t know, including the fact that clownfish are hermaphrodites from birth. Sorry to burst your bubble, but Finding Nemo is not an accurate guide to all things clownfish!

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Clownfish are anemone fish that belong to a class of damselfishes. What sets them apart from the rest of the class is the relationship they share with their homes. Sea anemones are marine animals that are commonly mistaken for plants since they have an undersea plant-like appearance. They also have tentacles that look like plant leaves. Their appearance and bushiness make them an ideal home for small fishes like clownfish. However, they secrete poisonous substance to defend themselves against unwelcome visitors. Interestingly enough, clownfish are immune to this venom and can happily co-exist with the anemones. Anemones protect them from bigger fish, and clownfish protect anemones from the butterfly fish that feed on them.


The process through which clownfish procreate is fascinating in itself. The “male” begins by dancing in front of the “female” to impress her. Once they decide they want to mate, they start cleaning a rock at the base of their sea anemone so the female can lay her eggs on it (They’re considerate fishes, and certainly don’t want homeless babies). They then expose their genital tubes to each other (weirdos!) and the female fish begins laying eggs in a circular pattern. The male fish follows her, fertilizing the eggs as he goes. Later, it is the male fish who cares for and protects the eggs, in addition to removing the debris of already hatched offspring.


Now comes the most amazing part. When the larvae hatch, clownfish babies have immature sexual organs of both genders. At birth, all clownfish are males. In case the mature male in the clan dies, the next immature/baby male becomes a mature male and mates with his biological mother. I’m sure this would make Freud very happy. Even more flabbergasting is what happens if the female accidentally dies. The mature male fish changes genders and turns into a female while the baby/immature male matures, and then mates with his father turned mother! Didn’t see that coming, did ya Freud? Counting the male to female ratio is quite difficult, given that they can spontaneously change gender.

It’s a wild and wonderful world under the waves, isn’t it? However, I’m very glad that Disney left out those details in the movie!


  1. Sea Anemone – Wikipedia
  2. Amphiprioninae – Wikipedia
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About the Author:

Rujuta has a MA in Counseling Psychology and MSc in Cognitive Science. She is currently pursuing a PhD in Cognitive Science from IIT Kanpur in India. Her primary area of interest being human memory and learning, she is also interested in the neuroscience of cognitive processes. She also identifies herself as a bibliophile and a harry potter fanatic.

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