A high-tech ichthyological version of a canary-in-the-coal-mine warning system is nearing market. It’s a system that monitors fish behavior as an early general warning of water purity problems. The system is being tested in several places, including New York City’s reservoir system, ahead of commercialization later this year.

The system, developed at the U.S. Army Center for Environmental Health Research at Fort Detrick, MD, uses bluegill fish to detect a broad range of toxic chemicals. It doesn’t look for anything specific; it detects anything that would stress a fish, from chlorine to cyanide. Each fish serves two-week tours of duty inside a plastic chamber containing two electrodes. The electrodes sense electrical signals from the fish’s muscle movements. During an initial calibration period, software learns an individual fish’s normal breathing rate and depth, gill movements, and overall body activity. During water monitoring, software detects departures from normal measurements, which can indicate the fish is stressed.

The advantages of using a fish is that it’s a 24-hour warning system that can call early attention to a broad range of problems, allowing officials to shut down a water system as a precaution. While the system cannot determine what’s bothering the fish, it does provide a general alarm, says the director of the monitoring program, William van der Schalie, an army toxicologist. “Traditional sensors may focus on one particular chemical. A fish biomonitor rapidly detects toxicity from a wide range of toxic chemicals and pesticides. It will tell you there’s a problem to look further into,” he says.

In testing by the U.S. Environmental Protection Agency in Cincinnati, OH, the system worked well, says Roy C. Haught, chief of the EPA’s water quality management branch. “Any time there’s a change in water quality, the fish detect it immediately,” Haught says. In the case of New York City, the system has been installed for homeland security purposes, to provide an early warning of chemicals introduced into the water supply. The system will be released commercially late this year by Intelligent Automation of Poway, CA. In the meantime, it needs refinement to weed out false alarms. As Haught puts it, “We don’t want to be crying wolf every time a fish coughs.”