Re: Do fish feel pain?

“Feeling “ pain has nothing to do with being warm or cold blooded.  All 
vertebrates have the same basic format to their nervous system that 
includes a sensory part that receives information from receptors out in the 
periphery of the body including the skin.  When a ‘painful’ stimulus is 
detected, the information is sent to the central nervous system.  When this 
information reaches the central nervous system, several reflex responses 
are initiated in all vertebrates.  The body part that has received the 
‘painful’ stimulus is moved in such a way that it gets farther away from 
the source of the stimulus.  This is exactly what happens when you step on 
a nail.  At the same time, the heart rate increases and the breathing (in 
fish, gill movements) rate increases.  In animals that can produce sound, a 
vocal response is also initiated (we say ouch).  This probably serves to 
inform neighboring members of the same species that a ‘painful’ stimulus is 
present in the area.  All of these responses are initiated without any 
conscious awareness or effort on the part of the animal.  However, the 
semantic argument says that these are not indicative of the animal having 
“felt” the pain.  “Feeling” involves processing by the cerebral cortex that 
allows the animal to make conscious decisions concerning what to do about 
the ‘painful’ stimulus.  In this respect fish do not “feel” pain because 
they do not have the cortex necessary to process the information.  So, from 
the semantic perspective fish reflexly respond to pain the same way all 
vertebrates do, however, they do not “feel” the pain the way we do.