Your Fish’s Brain on Drugs

Written by on July 25, 2014 in Marine Life

Antidepressants, some of the most commonly prescribed drugs in the world, are making their way into our waterways where they are messing with fish’s brains.

Cuttlefish displaying different colors and patterns. Photo credit: wwarby via photopin cc.

When exposed to antidepressants, cuttlefish won’t give up on their prey. Photo credit: wwarby via photopin cc.

A new study shows that drugs designed to ease the symptoms of depression, obsessive compulsive disorder, post-traumatic stress and other mental health problems can be damaging to aquatic species.

Antidepressants enter waterways from sewage and waste water systems, from human waste, and from people flushing unused drugs down the toilet. Researchers have found increasing concentrations of the drugs in rivers around the world, which is particularly dangerous because they can affect fish behavior even in tiny concentrations.

Many aquatic species are sensitive to these drugs because they produce serotonin, which is the same mood-influencing chemical that is altered by antidepressants. When exposed to small concentrations in lab settings, some fish become more aggressive and less cautious, while others became more attracted to light. In some fish, their ability to find food and reproduce was affected.

In one particular study, a test-tube containing a shrimp was lowered into a tank with cuttlefish. Ordinarily, the cuttlefish would stop trying to reach the shrimp, but after being exposed to antidepressants, they continued to slam into the tube, which is an enormous waste of energy.

The researchers note that the effects of the drugs should be tested at various doses before drawing conclusions.

“At the moment, it’s almost impossible for regulators to work out what is a safe level for these drugs in the environment,” Dr. Alex Ford from Portsmouth University said in a news release.

Dr. Ford notes that these problems are not limited to antidepressants — many of the hundreds of different drugs humans consume every day make their way into the environment. Some believe there ought to be changes made at sewage treatment plants in order to avoid these problems, while others think we should focus on the unused drugs to prevent them from being flushed away.

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Copyright © 2014 by Marine Science Today, a publication of Marine Science Today LLC.

About the Author

About the Author: Emily Tripp is the Publisher and Editor of She holds marine science and biology degrees from the University of Miami's Rosenstiel School of Marine and Atmospheric Science and a Master of Advanced Studies degree in Marine Biodiversity and Conservation from Scripps Institution of Oceanography. When she's not writing about marine science, she's probably running around outside or playing with her dog. .


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