Fish would eat you if they got the chance.

People's opinions will differ, and most people's won't be changed. Instead of a discussion, it will be people yelling at each other until they both leave angry.

Personally, I think it's not ethical to eat any meat, whether that is white, red, wet, or otherwise.
Other people have, and will, think it is ethical to eat all meat, including other humans.

Farmed fish is probably not too bad by comparison but.. wild caught fish hell no. We’re speed running fucking up the ocean ecosystem and ruining the aquatic biosphere. It always alarms me when I see a change to the species of fish used in “generic budget oven-cook battered fish fillets”. It doesn’t even seem possible to make wild catch fishing sustainable, unlike every other form of animal husbandry where you could argue it’s more of a technical challenge.

Hmm now I realise I’m a hypocrite. Think I’ll stop eating fish

I see two concerns, humanitarian and ecological. The ecological concern is only a problem with overconsumption. The humanitarian concern I don't think applies to fish since they are dumb.

Could depend on the fish species in question? Lionfish for example is extremely invasive in the Southern USA, so environmental agencies have been encouraging people to eat them to curb their population, potentially making it a more ethical choice. I've been seeing it pop up more and more, but it doesn't seem to have caught on too much.

But we should definetly limit our consumption though when it comes to more threatened/overfished species. There's also some unethical fishing practices out there such as removing sharks' fins then stranding them, causing harm to cetaceans, and other environmentally destructive fishing techniques.