Many people who walk through the Great Barrier Reef section of Sydney Aquarium have already heard of the symbiotic relationship the “Clownfish” has with the anemone.

The Clownfish picks off any small invertebrates as food that could potential harm the anemone and provides nutrients to the anemone by depositing fecal matter within the anemone. Any normal fish would most likely be stung, but the Clownfish is covered by a mucus membrane that the anemone does not recognize as food, it therefore provides a safe-haven for the Clownfish, protecting it from surrounding predators.

What we might not know is that all Clownfish are born as males, and can later change their sex to female. Generally a group of Clownfish will consist of a “harem”, one large reproductive female and one smaller reproductive male surrounded by even smaller non-reproductive males. If the female dies the reproductive male will change sex and become the female leaving the role of the reproductive, mature male to be taken up by the largest non-reproductive male in the group. A rather, unusual but very successful life strategy, that can be seen here at Sydney Aquarium.

So the answer to the question; Is Nemo a girl or a boy? It would most likely be that Nemo is a boy as he is a juvenile Percula Clownfish (Amphiprion percula). But he has the potential to join a small group of Percula Clownfish and take on the role as the girl or reproductive female.

If you were Nemo what would you do? Remain a boy or become a girl? Next time you make your way down to Sydney Aquarium have a look at our Tropical Marine displays that are home to a variety of different Clownfish, see if you can pick the female from the males.

🙂