“Normally, perch are shy and hunt in schools. This is a known strategy for survival and growth. But those who swam in oxazepam became considerably bolder,” ecologist Tomas Brodin, lead author of the article, explained. They “lost interest in hanging out with the group.”
He said that researchers conducted a “boldness test” on the perch, opening a door that would allow them to swim from a small box into a much larger water tank. The fish with no drugs in their system remained timid and “didn’t come out at all,” he said, while those on oxazepam did.
The researchers said those behaviors, coupled with the tendency to scarf down food faster than normal, could alter the composition of the species and lead to ecological changes in the real world. For example, if they consumed more plankton, it could lead to an increase in algae.