Fish in the coal mine

A cnn.com story discusses municipalities using sunfish as a "canary in the coal mine" against terrorist attacks agianst drinking water. Glad to hear we are actually doing something besides "fight them over there so we don't have to fight them over here."

SAN FRANCISCO, California (AP) -- A type of fish so common that practically every American kid who ever dropped a fishing line and a bobber into a pond has probably caught one is being enlisted in the fight against terrorism.

San Francisco, New York, Washington and other big cities are using bluegills -- also known as sunfish or bream -- as a sort of canary in a coal mine to safeguard their drinking water.

Small numbers of the fish are kept in tanks constantly replenished with water from the municipal supply, and sensors in each tank work around the clock to register changes in the breathing, heartbeat and swimming patterns of the bluegills that occur in the presence of toxins.