Do fish feel pain? Well they certainly feel something, otherwise they wouldn't react. If they didn't react and attempt to escape evolution would eventually weed them out, as would happen to any animal that had no survival instinct. But is it pain in the same sense that we feel? Uncertain, but even if it is there is one thing that we can be sure of - they do not feel the emotional anguish that we feel. Their brains are simply not capable of thought, self-awareness, or emotion. We fear pain as a sign that something is wrong, possibly fatal, and we only understand the meaning of 'fatal' because we are capable of complex communication. We have learned and taught each other, since our ancestors first learned to speak, that death is something from which we do not return (with the exception of certain religious beliefs). Such knowledge reinforces the fear of pain that we feel. Fish can never feel that emotional component, they are strictly reactive.