What did they forget to tell us about clownfish in the cartoon 'Finding Nemo'?

Explanation

In the cartoon 'Finding Nemo' they forgot to tell us an interesting fact about clownfish: they can change sex! Clownfish live in groups made up by one reproducing male and one reproducing female, as well as some non-reproducing males. There is a strict dominance hierarchy, based on size. The largest female is found at the top, then the reproducing male, then the smaller non-reproducing males. If the female dies, the reproducing male will change sex and become female. The largest non-reproducing male is then promoted to be reproducing.