There's a lot of anecdotes and some academic articles for well studied species about temperature and ph effecting sex in fish (and other animals), which I thought was weird enough.
Medaka are famous for being a well studied model organism, and for being the first fish identified to have human-like sex genes (think XX for female vs XY for male). But this article blew my mind and I hope some others find it interesting.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6382872/