Seventeen different prescription drugs have been found in a single fish in Florida during research into pharmaceutical contamination of marine species.

The findings are from a three-year study of bonefish in Biscayne Bay and the Florida Keys by Florida International University (FIU) and the Bonefish & Tarpon Trust (BTT).

The researchers examined the blood and other tissues of 93 bonefish that typically swim in shallow tropical coastal and island waters.

They found an average of seven pharmaceuticals per bonefish and 17 pharmaceuticals in a single fish. The list of medications includes blood pressure medications, antidepressants, medications for prostate treatment, antibiotics, and painkillers.

Drugs have also been found in species the bonefish feed on, including crabs, shrimp and other fish, suggesting that more Florida marine species are being exposed.

Pharmaceuticals end up in the ocean from human wastewater with contaminants insufficiently captured by water treatment plants.

Even at low doses, exposure to pharmaceutical drugs can impact fish behavior and impair reproduction, migration and survival.

Lead researcher Jennifer Rehage, a coastal and fish ecologist and associate professor at CRF’s Institute of the Environment, called the results “really alarming”.

“Pharmaceuticals are an invisible threat, unlike algal blooms or murky waters. Yet these findings tell us that they pose a formidable threat to our fisheries and underscore the urgent need to address our long-standing sewage treatment infrastructure issues,” Professor Rehage said in a statement.

The researchers noted that while five billion prescriptions are filled each year in the United States, there are no environmental regulations for disposing of these drugs globally.

And it’s not just Florida fish that are being affected by the drugs. A study, published earlier this year in the academic journal PNASfound pharmaceuticals present in more than 25% of test sites along 258 rivers around the world, including the Amazon and the Thames.

A quarter of the sites had contaminants, including the antibiotics sulfamethoxazole and ciprofloxacin, as well as the allergy drug loratadine.

Some of the most frequently detected active pharmaceutical ingredients at the sites included metformin, a diabetes drug, carbamazepine, an epilepsy drug, and caffeine.