It is controversial whether they feel the pain as mamals do, but they definitley feel the stress when hooked.

Good fisherman alway try to reduce the stress.

On the other hand, most fishes live stressful lives anyway. They need to constantly find food, shelter and avoid larger predators - so being hooked is just like a short episode in their life - just like people watching a horror movie and they do get out of the theatre in one piece happily:)