Fish behaviour is changing as a result of pharmaceutical product waste, according to a recent study. A team at Umeå University said that drugs excreted from the human body are finding their way into wastewater and making fish fearless, gluttonous and antisocial. Their work was published in Science journal.

Speaking to Discovery News, Jonatan Klaminder, a co-author of the report, said: "Fish, being vertebrates, often have the same drug receptors as humans. It is possible that many different kinds of human pharmaceuticals, or other chemical compounds for that matter, also have an effect on fish."

The team looked at how perch reacted to an exposure of oxazepam, which is commonly prescribed for anxiety, after finding traces of it in fish during a routine screening at the River Fyris, Sweden.

The report warned that, while other marine species could be affected by this drug migration, the impact in deeper water is limited as concentration levels would be lower.