Sydney, Aug 27 (IANS): Long-term exposure to pharmaceutical pollutants is dramatically altering the behavior and reproductive traits of fish, a study published on Tuesday has found.

In the study, a team of researchers from Australia's Monash University and the University of Tuscia in Italy found that fluoxetine, an antidepressant medication commonly known as Prozac, that has entered rivers, lakes and oceans via wastewater is changing how fish behave.

The five-year investigation focused on wild-caught guppies, one of the world's most widely distributed tropical fish.

"Even at low concentrations, fluoxetine altered the guppies' body condition and increased the size of their gonopodium, while simultaneously reducing sperm velocity, an essential factor for reproductive success," Upama Aich, co-author of the study from the Monash University School of Biological Sciences, said in a media release.

Additionally, exposure to the drug also significantly reduced the behavioral plasticity of guppies, lowering the capacity of individual fish to adjust their own activity and risk-taking behaviors across contexts, co-author Giovanni Polverino from the University of Tuscia said, Xinhua news agency reported.

The researchers said that the study highlights the profound and interconnected effects of pharmaceutical pollutants on aquatic ecosystems and the need to address pharmaceutical pollution.

To study the effects of fluoxetine on fish, researchers caught 3,600 mature wild guppies in Australia, where they are an invasive pest species, and randomly assigned them to three tanks.

Over five years each tank was dosed with different concentrations of fluoxetine, zero, a low dose at 31.5 nanograms per liter (ng/L) and a high dose at 316 ng/L, and studied the effects on the behavior, bodies and reproductive traits of the fish over multiple generations.

Male guppies were chosen for the study due to their heightened sensitivity to environmental shifts.