Nature is queer in every way imaginable. Diversity is the point.
If anyone is curious (as I was):
In real life Nemo’s dad would have become female after mommy got eaten. https://evolution.berkeley.edu/fisheye-view-tree-of-life/gender-bending-fish/
“of all the animals, fish are sexually the most fluid” - https://www.bbcearth.com/news/fish-are-the-sex-switching-masters-of-the-animal-kingdom
Salmon change sex too if I recall correctly.
I don’t think salmon change sex to be honest. It seems from the stuff I could find that sex determination for salmon is mostly chromosomal but with divergence at certain temperature during development (or exogenous hormonal influence obviously).
The coolest paper I found while searching was this:
Natural sex change in fish - ScienceDirect - https://www.sciencedirect.com/science/article/abs/pii/S0070215318301145
