A study led by Dr Lynne Sneddon, an expert in animal biology, showed that fish can exhibit symptoms such as hyper-ventilating and long-term behavioural changes after a painful experience.
Dr Sneddon, who is the director of bio-veterinary science at the University of Liverpool, said the results have “important implications" for how humans treat the animals.
Scientists reviewed 98 studies on fish pain to come to the conclusion that the animals do feel pain in a comparable way to mammals.
Pain in fish is a contentious issue, with some claiming that the animals’ nervous systems are not complex enough to perceive pain in a meaningful way.
“When subject to a potentially painful event fishes show adverse changes in behaviour such as suspension of feeding and reduced activity, which are prevented when a pain-relieving drug is provided,” Dr Sneddon said.
She added: “When the fish’s lips are given a painful stimulus they rub the mouth against the side of the tank much like we rub our toe when we stub it.
“If we accept fish experience pain, then this has important implications for how we treat them.”
Dr Sneddon said that steps should be taken to make sure fish are “humanely caught and killed” and the animals should be handled with care to avoid damaging them.
Although painful experiences are unpleasant, the feeling is an important survival tool for teaching animals to avoid injury.
"If fishes had no pain system then they would just go round damaging themselves,” Dr Sneddon told Newsweek.
However, a review by the University of Wyoming in 2013 concluded that fish were unlikely to feel pain, as they do not have a highly-developed neocortex needed to feel pain in their brains.
The University of Liverpool's paper was part of a series called “Evolution of mechanisms and behaviour important for pain” for the journal Philosophical Transactions of the Royal Society B.
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