In case you didn’t know, one of the best defenses our nation has put forward to combat bio-terrorism involves having our drinking water monitored by fish.

There’s no scientist taking daily samples or filtering system that’s supposed to send off alerts when certain substances appear in the water. No no, one of our most precious resources is being left up to fish.

As reported in the Washington Post this morning, water supplies in Washington, D.C., New York and San Francisco are being monitored using a system developed by the US Army and a private firm using bluegill fish.

Basically, a set of fish swim in their own little tank that has continuously changing water from the region’s water supply. The fish act normally when everything is ok–or at least as OK as the water ever gets. When a toxic substance is introduced into the water, the fish freak out, alerting a human to take some sort of action to prevent people from drinking the contaminated goods.

In case you’re wondering, the fish work for just two weeks before getting a vacation. I mean, we really can’t have the fish being overworked now can we? But I suppose if we are leaving our water supply up to a few fish that I could go catch myself, we want them to be in tip-top shape. God forbid we would have some other way of measuring if there is something toxic in the water.

Though we don’t know exactly how many people are being serviced by the bluegill detectors–for security reasons, of course–at least 4.5 million people in the D.C. area have been drinking the fish-monitored water for at least six months now.

I definitely feel safer.