Maybe some fish will survive a rapid change in their ecosystem. I'd be worried, that most probably will die when their capacity to adapt is exceeded either dire

Maybe some fish will survive a rapid change in their ecosystem. I'd be worried, that most probably will die when their capacity to adapt is exceeded either directly or through breakdown of food chains. Though I'd be more worried about effects like seasonal oceanic dead zones increasing in size and persisting longer. I don't think too many fish will evolve into a species not requiring oxygen anytime soon.