Similar effects have been seen in humans who take the antidepressant. Common Prozac side effects include a decrease in sex drive, impotence, or difficulty having an orgasm, according to WebMD and Drugs.com.
Fathead minnows are small fish, the biggest ones measuring only a couple of inches long. Their small size could be a factor in how they react to low levels of Prozac. However, Klapper believes that the concentrations used in this experiment, as well as the levels seen in the environment, could also impact larger species of fish.
“Fish don’t clear the medication as quickly as other animals,” she says, which can lead to a possible build up of Prozac ultimately changing the fish’s behavior.