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Murray Edwards College
University of Cambridge

School Winner: Do Fish Feel Pain?

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    30 Nov

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    I’m sure when you think of a fish, the first word that pops into your head isn’t ‘fascinating.’ Fish certainly aren't the most loved animal on the planet, and you'd think that they definitely wouldn’t be the most physically pained creatures. Whilst a fish obviously has a lack of conscious feeling compared to mammals, it is a common misconception that they do not feel pain of any kind.

    Whether you're talking about the tiny- brained minnow or the rapacious shark, every single fish has some form of feeling, which is fascinatingly separate from how we feel as humans.

    Within a fish there are just two types of nerve fibre that may support the idea of pain. Group C nerve fibres are sensory nerve fibres which have an unusually small diameter, resulting in a low nerve conduction velocity. The feeling of a burn or a toothache experienced in us humans is due to C fibre activity. Bony fish have been shown to also have A- delta fibres which carry pressure and a low number of pain signals. This research suggests that fish may feel pain in a similar way that humans do.

    A study which took place in Forschungsverbund, Berlin has shown that unlike humans, fish do not possess certain nerve fibres in mammals (known as c- nociceptors) which have been proven to be a key factor in experiencing intense sensations of pain. However, this study has shown that bony fish possess simple versions of these nociceptors and have had clear reactions to injuries. Physiologist Lynne Sneddon discovered that trout had a total of 58 nociceptors in their lips alone. Despite this it is not known whether the pain being experienced is conscious or an unconscious reaction in which nerves cause the body to move, not including any sort of mental engagement.

    This leads to the question of if you can regard unconscious pain as a feeling the fish is experiencing, or if it’s simply a reflexive response.

    Whilst empirical experiments on live fish may raise ethical concerns, painkillers like morphine have proven ineffective or only effective in abnormally large doses on fish. However, these large doses result in the fish dying from shock. These findings suggest that fish have no awareness of pain or the amount of pain the fish is feeling is almost inconsequential. However, Ehrensing

    demonstrated that morphine prevents goldfish from learning to avoid electric shock. This experiment suggests that fish find electric shock painful, and providing pain relief prevents the pain from being experienced so they fail to learn.

    Within this question, we must ask ourselves; how much do we really want to know the answers to these questions, which may have profound ethical consequences? And if we were to discover that fish feel pain as we do, would that motivate us to change our behaviour? In any event, despite the extensive amount of research being put into this topic, we still do not have a definitive answer. The evidence I have cited appears to be contradictory and it seems there is more research needed to give us the satisfactory evidence to reach a conclusion.

    Melissa Saphra
    St Marylebone's CE Sixth Form School

    "Hi, my name is Melissa and I’m currently in year 12 studying Biology, Geography and English Literature. In a few years time I hope to be studying Zoology or Marine Biology at university. For my whole life I have been completely fascinated by fish- especially the weirder deep sea creatures- so writing a blog all about them was incredibly interesting for me.

    In the future I would love to find new ways of protecting our oceans, and also help to find out more about the abyssal zone and what’s down there. I think the thing that draws me to the ocean the most is the complete mystery that comes with it!"