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Bad news for the fish in Florida. As human wastewater makes its way into oceans, the fish are testing positive for a mess of pharmaceuticals!

Researchers at Florida International University and the Bonefish and Tarpon Trust studied the two types of fish found in Biscayne Bay and the Florida Keys since 2018. They found that every single one of the 93 fish collected and tested had an average of seven drugs in its system. 

The 93 collected blood and tissue samples were tested for human drugs, including antidepressants, blood pressure medications, prostate treatment medications, antibiotics, and pain relievers.

The study found that one fish even had a shocking total of 17 different drugs in its tissues. What’s more, the researchers found pharmaceuticals in the bonefish prey – including crabs and shrimp.

Of course, these drugs can — and will — affect every aspect of fish life, including their feeding habits, sociability, and migratory behavior, which is a massive threat to the already shrinking bonefish population in the area.

Jennifer Rehaga, a coastal and fish ecologist and associate professor at the university, said in a statement, “These findings are truly alarming. She explained that “pharmaceuticals are an invisible threat, unlike algal blooms or turbid waters.” 

“Yet,” she adds, “these results tell us that they are a formidable threat to our fisheries and highlight the pressing need to address our longstanding wastewater infrastructure issues.”

The study said that nearly 5 billion prescriptions are filled in the United States every year. And IQVIA reported that in 2020, 6.3 billion prescriptions were dispensed.

This well-timed study comes only three years after a similar study published in Biology Letters in 2019 in Australia found that fluoxetine, the main ingredient in the antidepressant Prozac, disrupts the foraging behavior of a freshwater species of Mosquitofish. They are found in both the United States and Australia.

Researchers found that exposing both individual fish and their social groups – called ‘shoals’ – to different levels of fluoxetine had no apparent effect on solitary fish.

However, as a group, researchers found that the Mosquitofish relaxed their hunting behavior and ate less food overall when exposed to high levels of the drug. Fluoxetine remains active even in low doses and can be released constantly.

Despite this growing body of data, there are still no environmental regulations for the disposal of pharmaceuticals. Simply thrown away or flushed down the toilet, they inevitably wind up in freshwater bodies like lakes and rivers. The water treatment systems cannot fully filter out the traces of the drug… and that means they’ll continue to wind up in fish.