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Prozac, a commonly prescribed drug to treat depression, panic, anxiety or obsessive-compulsive symptoms in humans, does quite the opposite in fish.

Scientists found that minnows swimming in waters with low levels of the antidepressants exhibit edgy, hostile and even "homicidal" behavior.

Researchers from the University of Wisconsin-Milwaukee found that environmental exposure to antidepressants like Prozac and Zoloft dramatically altered the behavior of fathead minnows, a common freshwater fish found in ponds, streams and small rivers throughout the Midwest.

Fish exposed to these antidepressants began exhibiting reclusive behavior and were sluggish and unmotivated when attempting to catch prey, according to an article published in the Scientific American.

Researchers found that the reproductive levels of the fish also decreased because they spent more time alone.  Researchers said male minnows appeared to ignore females, and often attack and even kill female minnows.

Researchers said that the doses used in the experiment were just one part per billion, which is considered to be a very low concentration. Researchers found that when the antidepressant dose was increased to a higher level, female minnow produced fewer eggs and males became more aggressive.

Lead researcher Rebecca Klapper said that this troublesome experimental finding could actually be happening the wild.

She explains that people do not completely metabolize medications, so trace amounts of drugs excreted in urine often end up in waterways and affect wildlife because water treatment centers cannot completely filter out all contaminants.

Scientists said the levels of drugs tested in the experiment are similar to those found in public waterways.

In a 2012 Society of Environmental Toxicology and Chemistry conference, Klapper said that scientist have even found "architectural changes" in the brains of young minnows exposed to trace amounts of antidepressants.

"It's not just an environmental question but a human question as well," she told ABC News.

She said changes in reproduction behavior were seen in minnows exposed to concentrations as low as 1 microgram per liter, which is equivalent to a single dose of Prozac dissolved in over 5,000 gallons of water.

Similar effects have also been seen in people who take the antidepressant.  Some side effects of Prozac include decrease in sex drive, impotence, or difficulty achieving orgasm.

Experts are not completely sure how pharmaceuticals in water affect humans and wildlife.

In 2012, the World Health Organization released a report that state that "trace qualities of pharmaceuticals in drinking water are very unlikely to pose health risks," according to the Daily Mail.

WHO researchers found that pharmaceutical levels found in drinking water is on average 1,000 times less than the doses that would affect humans.

However, the latest research suggests that the same cannot be said for fish.

Researchers explain that fish, particularly fathead minnow are small.  The largest minnows measure only about a couple of inches long. Researchers said their small size could be reason why they exhibit such dramatic behavioral changes to low levels of Prozac.  Klapper believes that the concentrations used in the experiment as well as the levels seen in the environment could also affect larger fish.