I’ve understood that fish feel pain since I was a kid and my brother took me fishing. I caught a fish and I screamed at my brother to take the hook out of its mouth and put it back in the water. He made me take the hook out and I freed it. As it flopped about with eyes filled with horror I knew just like anyone with half a brain, that the poor animal felt pain. I don’t really know what my ten year old self expected, but I never ate fish again.