The detection of pain and fear in fi sh has been subject to much debate and, since fi sh are a popular experimental model and commercially important in both angling and aquaculture, many procedures that fi sh are subjected to cause injury, fear and stress. These injuries would give rise to the sensation of pain in humans but whether fi sh have the capacity for pain is relatively under explored. Recent evidence has shown that fi sh have the same neural apparatus to detect pain that mammals and humans do, that their brain is active during a potentially painful experience, that fi sh show negative changes in behaviour and physiology and that this is reduced by administering a pain killer. Experiments demonstrating the signifi cance of pain to fi sh have been conducted and have shown that fi sh do not show appropriate fear and anti- predator responses during a painful stimulation. This suggests that they are dominated by the pain state confi rming its importance to the fi sh. However, social context affects the aggressive behaviour of fi sh when noxiously stimulated. In a familiar group, dominant trout perform much less chasing of conspecifi cs yet this suspension in aggression is not seen when placed in an unfamiliar group of fi sh. Therefore, responses to pain are more complex and not simple refl exes. Together, these results demonstrate that pain is an important stimulus for a trout and we should seek to minimise and alleviate pain where possible. Studies have demonstrated that fi sh are capable of exhibiting signs of fear including avoidance behaviour and they may also anticipate fearful events. Recent evidence shall be discussed with future directions suggested.
Sneddon, L. (2013). Do painful sensations and fear exist in fish?.