"Prozac pollution" remains a potentially dangerous long-term problem that fish and aquatic wildlife still have to contend with.

Prozac (generic name fluoxetine) remains a popular antidepressant used for the treatment of major depressive disorder, panic disorder, obsessive-compulsive disorder (OCD), bulimia nervosa and premenstrual dysphoric disorder. It entered medical use in 1986 and remains on the World Health Organization's Model List of Essential Medicines, which consists of the most effective and safe medicines needed in a health system. Prozac is available as a generic medication.

While Prozac has been proven safe for human use, there are still questions about its long-term effects on acquatic wildlife. Surprisingly, one of the effects of prozac on marine wildlife might be similar to that in people. One of the possible side effects of Prozac use among humans include decreased libido and sexual dysfunction. New research into the effect of Prozac on fish seems to suggest the drug might be making fish less sexually aggressive and lazier in their hunt for food.

A study on the impact on psychoactive drugs (including antidepressants) on the social behavior of fish conducted by Australia's Monash University was recently published in the journal Biology Today. Among other findings, it found that pharmaceutical pollution in waterways is having a "disturbing impact" on fish.

More disturbingly, the study found that psychoactive drugs are altering the reproductive behavior, anxiety levels and anti-predator responses of fish in the wild.

"Our research found that the antidepressant pollutant fluoxetine (commonly marketed as Prozac) did not alter behavior of solitary fish," Dr. Jake Martin from the university's school of biological sciences said. "But in a group setting, fluoxetine exposure disrupted the frequency of aggressive interactions and food consumption."

Put in another way, Prozac didn't change the feeding and foraging behavior of solitary fish, but when it was applied to whole groups of fish, it had a suppressive effect.

Prozac pills
Japanese researchers show that chronic use of the antidepressant Prozac can induce a juvenile-like state in the prefrontal cortex. Tom Varco, CC-BY-SA-3.0

Dr. Martin said these results are significant because they suggest behavioral tests in social isolation might not accurately predict the environmental risk of chemical pollutants for group-living species such as fish.

A 2018 study from the University of Ottowa about the impact of Prozac pollution on fish said it could last for three generations. In that time, the antidepressant blunted the stress responses in exposed embryos and any of those embryos' descendants once it had matured.

The study showed how zebrafish didn't explore their tank as much when they were treated with Prozac. Dr. Vance Trudeau, a neuroendocrinologist, said there are good reasons to assume the effects his study revealed might also occur in humans.

This remains a possibility because the core stress hormone cortisone has the same impact in fish as it does on humans.