Do fish feel pain? © Getty Images

Do fish feel pain?

Asked by: Keith Anderson, Bradford

It’s an old adage that fish don’t feel pain. Their brains are too small and simple – or so the story goes. But evidence is stacking up to the contrary.

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In 2003, researchers at the Roslin Institute near Edinburgh discovered sensory nerves in bony fish that allow them to detect pain in a similar way to birds and mammals, linking their skin and other areas of the body to the brain. The same team went on to find that, when injected in the lips with mild acid or bee stings, rainbow trout rocked their heads and rubbed their lips against the aquarium tank. Given painkillers, the trout behaved normally again.

Many other studies reveal aspects of fish suffering, including in cramped fish farms where some salmon stop feeding and show signs of depression, such as high levels of the stress hormone cortisol.

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