Fish Can Feel Pain Like Mammals, Scientist Says

Fish experience pain on a level comparable to mammals, according to a scientist who has debunked the common misconception that the animals aren't capable of such sensation.

Lynne Sneddon, director of bio-veterinary science at the University of Liverpool, conducted a review of existing research on fish and pain. Sneddon published her findings in the journal Philosophical Transactions of the Royal Society B.

The expert in aquatic animal biology looked at 98 studies on fish pain. The research showed how similar receptors in fish are to those found in mammals—partly evidenced by factors including how the sensation alters their behavior and how it can be treated with painkillers—and led Sneddon to overwhelmingly conclude fish can feel pain.

"The review shows that from the underlying genes, physiology, to whole animal behavior, that fishes have a very similar pain system and express similar behaviors when compared with mammals," Sneddon told Newsweek.

In 2002, Sneddon identified receptors that detect painful stimuli in rainbow trout, showing that fish do indeed feel pain.

"There is convincing scientific evidence, not just from my laboratory but from other researchers, that confirms my findings that fish experience pain thereby dispelling the myth that they don't," she said.

Although unpleasant, feeling pain is an important tool for survival as it helps animals avoid injury. By remembering the source of the pain, an animal can avoid the same danger in the future.

"If fishes had no pain system then they would just go round damaging themselves." said Sneddon, adding this would likely cause them to die.

Animals can't communicate with humans so scientists must rely on signs like changes in their behavior to study pain.

Sneddon has also previously looked at behavioral and physiological changes when fish were exposed to potentially painful stimuli. They responded by not eating, quickly beating their gills, and not taking part in their usual activities. "All of these changes were prevented by the use of pain-relieving drugs," Sneddon said.

Asked whether humans cause fish pain by fishing for food or angling, Sneddon said: "There are many ways that we cause tissue damage to fish that may give rise to pain such as in recreational angling, aquaculture and fisheries and so we should seek to improve the way fish are treated in these contexts."

"I would hope people would treat fish with more care especially in recreational angling and large scale fisheries," she said.

"Fish are caught in huge numbers and can be brought up from depth too rapidly such that their swim bladders burst, they can be crushed under the huge weight of all these fish, suffer injuries in trawling and then can be killed by suffocation in air, live chilling or on ice."

Sneddon added: "All of these are likely to cause pain."

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A stock image shows two ocellaris clownfish and a blue sea anemone. Getty