Although science shows fish do feel something quite like pain, and it can be dulled with drugs as in humans, there are nontrivial biological differences between

Although science shows fish do feel something quite like pain, and it can be dulled with drugs as in humans, there are nontrivial biological differences between that sensation and mammalian pain. So I suppose it depends on one's definition for "pain." The evidence for pain in fish: the use of morphine as an analgesic, 2003. http://www.appliedanimalbehaviour.com/article/s0168-1591(03)00113-8/pdf http://www.appliedanimalbehaviour.com/article/s0168-1591(03)... Do fishes have nociceptors? Evidence for the evolution of a vertebrate sensory system, 2003. http://rspb.royalsocietypublishing.org/content/270/1520/1115 http://rspb.royalsocietypublishing.org/content/270/1520/1115 Thermonociception in fish: Effects of two different doses of morphine on thermal threshold and post-test behaviour in goldfish, 2009. https://www.sciencedirect.com/science/article/pii/S0168159109001051 https://www.sciencedirect.com/science/article/pii/S016815910... Can fish really feel pain?, 2012. http://onlinelibrary.wiley.com/doi/10.1111/faf.12010/abstract http://onlinelibrary.wiley.com/doi/10.1111/faf.12010/abstrac...