I buy it. I believe a fish thrashes when caught because it is instinctively trying to escape a predator.... us. if you take the statement about feeding and resuming normal activity soon after being caught and you apply it to other living things we know feel pain, it is not the same. When humans, dogs, cats, ect get hurt, the last thing on their mind is feeding or grooming or making their bed. they go into a semi state of shock for lack of a better word. They shut down all normal activity.
What they are saying if a fishes brain is not advanced enough to process pain. They sense something is wrong but there is not true pain.
I too agree.. our own brains are wired to receive pain signals from our bodies, however, the brain itself is not receptive to direct pain signal induction (meaning that it can be probed w/o pain)
It is the pain receptors our brain reacts to from connective tissues throughout our bodies (nerve ganglion branches) from our spinal cords react to alert the sympathetic nervous system that then alert the immune system to get a move on cuz something is not quite right...thats alot of brain power..heck if fish were that smart we would never catch em..
With a fish having such a small brain, I can see where the science had beneficial results on non pain reception or display of said pain on normal activities wired into the fish brain...
Strong stuff.. perhaps someone in Biotech will research this and may develop a new "fishvill" anti head ache pill that will compete with advill, motrin and tylenol...never say never!!