Some fish are showing signs of drug exposure that scientists never expected to find outside a pharmacy.

It’s not just plastic and oil changing what lives beneath the waves. In rivers, lakes, and coastal zones, fish are testing positive for everything from antidepressants to blood pressure meds. And they’re not swimming through it by accident. The source is us—our toilets, our showers, our prescriptions flushed, expired, or excreted, all making their way into the waterways. Wastewater treatment plants weren’t built to screen out trace pharmaceuticals. So the drugs we use for anxiety, cholesterol, or sleep are now mixing quietly into aquatic ecosystems, changing the behavior, chemistry, and survival of fish across the planet. It’s subtle. It’s cumulative. And it’s already happening faster than regulators can respond.