If thinking that way works for you, than have at it. It shows even the intelligence of science seems to be missing at times. My opinion is that they do feel pain, maybe not in the same sense as humans but they do. I had the same discussion with an individual that felt that it was proper to shove a BB fork into a live lobster and roast him in the fireplace because he didn't feel pain! Get real. I'm happy for all those Brit cousins whose conscience can rest on this topic. Form your own opinion, this is mine.
Pain is the brain's psychological interpretation of a sensation. The interpretation of pain is located in the higher cortical areas of the brain. We know that by functional MRI imaging. These are located in areas that fish do not have. Therefore, it is impossible for fish to "feel" pain as a human understands pain,
They do feel the hook but they react in a very different way than humans would. They pull against the hook, a human would never do that. Pulling increases pain in a human. If fish feel pain, why do they pull against the hook?
Professor Rose of the Department of Zoology and Physiology wrote the definitive article on pain comparing the human brain with the brain of a fish in 2002.
Subsequently a panel of researchers and neuroscientists determined in 2013, that indeed fish do not have the capacity to feel pain and extremely unlike that pain exits for fish. In fact, neural blockers of pain have no effect in fish because they do not have the brain structures that these blocker work on.
"In their research, scientists from Europe, Canada, Australia and the United States come to the conclusion that fish probably do not have the people like pain. The researchers found that fish, unlike humans, do not have a cerebral cortex and missing that other essential organoleptic prerequisite for a conscious experience of pain. In particular, the key for the pain C-Schadenszeptoren (nociceptors) are missing in all studied primitive cartilaginous fish such as sharks and rays entirely, and they are extremely rare in all bony fish such as trout and carp. Also show fish no significant behavioral responses when faced with horrendous human interventions. Most painkillers fail their service in fish. Prof. Dr. Robert Arlinghaus concludes, that "bonefish have no doubt with simple nociceptors, and they show self-evident reaction to injury and other interventions, including. on forward-avoidance reactions. Whether these are, however, perceived as pain, is not known and quite unlikely, in our research."
For fish to feel pain, an entirely different mechanism that gives fish consciousness is needed. Those who believe that fish do feel pain speculate that fish might have developed consciousness somehow without higher brain anatomy; but all of musings are speculative. Using what is known and demonstrated, the best knowledge is that fish cannot feel what humans and mammals know as pain.
Read what Wikipedia says about fish and pain especially the sections on neuroscience and neuroanatomy. Pain exist in the brain and is very different from a withdrawal reflex that occurs when a person is unconscious.
We humans want to understand everything but also tend to anthropomorphize our perception of other animals. Trout have boney plate mandibular structure adapted to ingesting caddis larvae incased in little rock bits, crayfish and other gnarly organisms besides succulent little mayflies. Their brain is more a nerve ganglia monitoring pressure change, orientation in the water column, etc. than a complex thought center like ours. No doubt they do not "feel" pain, interpret light wave color or anything else like we do nor do birds or pet dogs, each having their own evolutionary developed senses.
Still, I have little doubt that in their own fishy way, it does not make their day to be yanked around by a non-understood hook or held out of their watery habitat to have it carefully removed (boy, the soft tissue mandibular structure support damage I observed on a high percentage of wild fish I brought to hand this past month seemed greater than ever). When you watch a male and female trout prepare a redd then writhe together, mouths agape during spawning it "looks" like they are experiencing pleasure...perhaps, for our quarry's well being, it is better if we indeed DO perceive they are experiencing their own, trout expression of pain. Will that make us less inclined to hoist them into the drift boat, yank out the hook via twisting it, hold them aloft forever for a two-hand-held-forward photo session, then drop them in the boat to flop about till the guide can pick then up in an effort to get them back in the water...well, in addition to pain, fish have no ego either.
Since this can truly only be educated speculation (until fish can speak), let me pose this to you. Which would be worse "to you?" (any of you):
A. Someone out of the blue sticking you (no need to be graphic) and then running off.
B. Someone sticking you, and then dragging you by the wound down the road a 1/4 mile taking 10 minutes to do so, and during that entire time you are absolutely sure that this is it, you are going to be slaughtered as you fight and try to get away in absolute terror.
Now I won't speak for you yet I'll choose "B" as being worst. I would also struggle and fight to get away regardless of the pain (as to suggest that a simple wound would cause you to freeze up and quit is ridiculous for most).....Yet the worst of it would be the absolute terror that makes you not only struggle to try and get free then to flee, yet the fact I know in my heart I'm going to die horribly if I do not.
So the fear.
Believe me, hook me in the mouth and drag me along I'll try and fight it and if losing a cheek yanking against it is my only option to survive, well then I'll have a Joker's smile....Contrary to assumptions. Yet the fear by far would be the worst of it and if you have never experienced that degree of fear, my most sincere happiness for you, may you never.
So whether they feel pain, IOW interpret it the way we do I find a secondary consideration at best.
But hey, whatever helps someone get by is their business.....I on the other hand prefer to take full responsibility for my actions, just or no of no matter in that eternally questioning myself and regret keeps me from becoming a monster.
Fish eat snails, oysters *(not on the half shell, but crunched up in their mouths/throats, catfish, bluegills, stingrays,, sea urchins, crayfish, etc. and don't complain, they go back and do it all over again ten minutes later. Of course, people go out and willingly apply for next day's hangover again and again)
Pain vs. discomfort? I've been through a lot more pain than 99% of the population and it seems I still go back for more (How fully you live your life is directly proportional to the number of trips to the ER)
Getting caught and released is probably to them about like playing a football game or being in a boxing match, except that they don't know the outcome or the lack or reason.
If they could think and talk I'd imagine that they would tell you that getting caught and released on a barbless fly is a lot better than being gill netted and fried. Of course if they can't think, then why is it we have trouble catching them?