Only if eating ethically is defined binary, not on a gradient.

A huge portion of harm can be reduced/prevented with only a little effort. Don't let perfect be the enemy of good.

> "Don't let perfect be the enemy of good. "

Battle cry of the conservative party lately. This quote has its place but not in the context of this conversation.

It beats doing nothing. Vegetables are harder to avoid eating at all, but fish? You can totally do without eating any ever again and be fine. And almost all salt you can buy in stores has iode added so you won’t miss that nutrient.

There's no known dietary replacement for some essential nutrients that come from eating fish. Even fish oil pills aren't as effective.

Fish oil pills don’t solve the issue anyway, they’re made out of fish.

Be that as it may, by not eating fish you’re also not absorbing as much heavy metals which fish is rather rich in these days.

Not entirely true. Buy produce from your local organic farmer at the farmers market and you'll probably be fine ethically.