For an individual perch, a little less anxiety may be good if it leads to faster feeding. But such alacrity may also have unintended consequences, either by setting off a cascade of faster consumption of algae-eating zooplankton throughout the food web, thereby allowing more algal blooms in the ecosystem or simply by exposing individual perch to more predation. Fish without fear are fish that quickly get eaten by larger predators, such as pike.
It remains to be seen what the overall effect of the pharmaceutical contamination may be, although it has been going on for decades since benzodiazepines were first prescribed in the 1960s. But instead of flushing old drugs, the better bet is to return them to pharmacies for proper disposal as well as, potentially, develop new treatments for sewage facilities that can filter out the drugs coming into the water via human urine. "There are several ongoing research projects that try to develop more efficient removal techniques, such as using ozone," Fick told Scientific American in an e-mail. Otherwise, human antianxiety drugs may provoke yet more anxiety about the environment.