Environment Magazine

Anti-Anxiety Drug Makes River Fish Anti-Social

Posted on the 15 February 2013 by Earth First! Newswire @efjournal

by Russ McSpadden

Oxazepam is a popular pharmaceutical that has been prescribed and used extensively–beginning in the 1960s–to treat anxiety, insomnia and a host of symptoms related to alcohol withdrawal. Traces of it pass from the drug’s user to the toilet and get flushed into water systems that find their way into rivers where they remain biochemically active. Until now the effects on wildlife have not been known.


Recently, a team of Swedish researchers discovered that oxazepam flushed into the wild has a similar effect on fish as it does on humans–they become less social, eat more, and are bolder–raising terrifying questions about the ecological impacts on wild fish populations.

The scientists were able to study the changes in behavior of European perch by recreating the oxazepam levels they found in wild river in a controlled aquarium setting.

“[Fish] exposed to water with dilute drug concentrations…exhibited increased activity, reduced sociality, and higher feeding rate,”  the team noted “As such, our results show that anxiolytic drugs in surface waters alter animal behaviors that are known to have ecological and evolutionary consequences.”

The altered behavior of the perch, which normally hunt in schools, indicates that they may now be less adapted to their environment.

The full study conducted by scientists at Umeå University in Sweden is published in the journal Science.

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