Absolutely there are. Many (or most) of the people who catch fish, pour coke onto the mortal wound they just created for their own leisure and toss them back into the water to die would confidently tell you fish are incapable of experiencing pain.
A quick google suggests they think it helps stop the bleeding..
It's hard to reconcile that you'd be willing to rip an animal from the sea to kill and eat it, or just for the fun of it, but also care about the animal though to conduct some insane little ritual of pouring soft drink on the wound you created to try and help it survive.
Growing up I'd be forced to go fishing with my dad a lot. When we'd catch a fish that was the wrong species, he'd whip it against the side of the boat and watch it float off while laughing with his friends.
I doubt the knowledge of consciousness, pain, or any other harm caused by hunting or fishing would dissuade most that do it regularly (in my anecdotal experience)
