Traces of anxiety drugs in water may affect the behavior of fish a new study suggests.
Researchers in Sweden found that fish exposed to anti-anxiety medication were less social, hyperactive and ate more quickly than those fish that weren't.
The study had researchers expose wild European perch to various concentrations of Oxazepam, reported the New York Times.
Traces of the drug had significant effects on the fish.
"Normally, perch are shy and hunt in schools," said lead author Tomas Brodin, reported Science Daily.
"This is a known strategy for survival and growth. But those who swim in Oxazepam became considerably bolder."
They also became less social and took greater risks by swimming without their school.
It is still unclear how this might disturb the ecological balance but scientists had a few theories.
"In waters where fish begin to eat more efficiently, this can affect the composition of species, for example, and ultimately lead to unexpected effects, such as increased risk of algal blooming," Brodin said, according to AFP.
The findings were published in the journal Science.