I read somewhere that they do have pain receptors and feel pain, but it doesn't register the same way as it does in higher vertebrates. this is especially true in sharks.
I'm not saying you're wrong; I'm saying there's a middle ground between you and the poster you're replying to, and that sticking to absolutions that are VERY difficult to measure is at the least, unwise. their nerves are more spread out than ours AFAIK so they feel pain, but less intensely, and they're less likely to feel pain from a hook because of the lower nerve density.
think of the human back: there are fewer nerves in your back and they're more spread out, so people can do crazy stunts like put hooks through themselves but being whipped or slapped still hurts. same with the skin on your elbows.
and, yes, fish show the capacity for situational learning, but not the capacity for reasoning. their cerebrum is flat and tiny. they react, but they don't think.
I still believe in respecting fish, and try not to subject them to undue stress and handle them as gently as possible until I release or kill them, but I wouldn't describe them as salient. more like, barely conscious.