Fish fed extremely low concentrations of an anti-anxiety drug eat more quickly, act more boldly, and socialize less than their un-medicated peers,
Bent Christensen / AP
Drugs taken by humans can have unintended side effects — on fish, in the natural environment. Turns out, fish fed extremely low concentrations of an antianxiety drug eat more quickly, and act bolder and more antisocial than their un-medicated peers, a new study finds.
"We can see profound effects at the low levels that we find in surface water. Exposed fish are more bold," Jerker Fick, a co-author and researcher at Umea University in Sweden, said at a news conference here at the annual meeting of the American Association for the Advancement of Science (AAAS).
The study looked at the effect of oxazepam (also known as Serax), used to treat anxiety and panic in humans, on the widespread European perch fish. Researchers gave the fish a concentration of drugs similar to that found in rivers and streams in Sweden and elsewhere, according to a study published today (Feb. 14) in the journal Science.
Here's how the drugs make their way into fishy habitats in real life: They get excreted by humans, pass through wastewater treatment facilities, which are not designed to break down such compounds, and then flow into rivers, Fick told LiveScience.
In the lab, perch were exposed to oxazepam in aquaria meant to mimic the animals' natural conditions. Once exposed, the fish became more antisocial, distancing themselves from fellow fish and likely putting themselves at greater risk of predation, said co-author Tomas Brodin, also of Umea University.
Exposed fish also ate more quickly, a trait that could have profound effects on the environment. This quick gobbling of zooplankton (tiny floating animals) could perhaps lead to blooms of algae, which zooplankton eat. If perch devour more zooplankton, more algae could survive, and their populations could explode, Brodin said.