I agree with your running over a dog example.

I’m leaving the son/LA example at the wrong level (ie not comparable to supplying all LA with water) on purpose, because I think your whole point (which was correct!) is that the 30 fish weren’t at that level either!

I think “the same level” is sweeping the entire problem under the rug. Is there some way that fish could be at the same level as burning down LA? I guess maybe, if it was literally all the fish in the world forever. I think I agree with you that we will basically never reach that level, and that the correct thing to do is to prioritize humans over fish when they’re at the same level, and maybe, tentatively, in some cases, prioritize the fish when it’s obviously a totally different level (eg all the fish in the world vs. one human’s stubbed toe).

I think this is sometimes attainable though. Nine billion chickens are tortured in factory farms each year so people can eat chicken nuggets. Is that the same level, or not? I’m not sure. I just want to make the point that debating these questions doesn’t require us to say animals have literally zero value - just place them on a lower level than humans.