It depends greatly on the fish whether they feel pain or not. A majority of the fish that we keep in our aquarium, do not feel pain. They have the nervous system's, complex enough to do their daily chores of eating, breathing, swimming, etc. But their nervous systems are indeed not complex enough to feel pain. But they can feel stressed, which is the main issue with fishing.
Larger fish, may very well feel pain. But I have serious doubts against the fact that they feel more emotion than being safe or in danger. But then again, I have never looked at a study that says they can, besides the marine mammal of course.
Meh, I got to get to work. In short, I think if your gonna catch a fish, fine, catch and release. The fish will be stressed for an hour or so, and then be on it's merry way. If you wanna catch it and eat it or keep it, fine, just make sure you have the license to do it.
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The only difference between the animal and the human, are the letters that they are spelled with.