Not knowing and not caring are different things. Do you care if the
grass hurts when you walk on it? Do you care if a housefly suffers
needlessly when its plastered up against the sunny window in your
kitchen? Do you care how the WORM feels when its being dangled in front
of the fish?

Pain and suffering are a reality of life for every single species of
animal life on the planet. Humans may be unique in their ability to
reduce pain for humankind; that makes our particular trait rather
unnatural. To grant this to pets and other animals we have made a
personal bond to is touching, but a bit specie-centric. To extend this
to fish you are catching with the intent to kill and eat would be way
outside the rules of nature, it seems to me. They wouldn't do it for
us.

--riverman