Several water processing plants in the Netherlands use Ide as a biomonitor. (I've personally seen them in one of the water plants for the city of Groningen). These fishes naturally swim against the flow, except if there's a reason to flee, like a sudden change in water quality. By placing a number of fishes between two touch sensors (front and rear) in a pipe with flowing water, you can monitor the flight-response. The fishes will softly boop the front sensor in their usual swimming. Once the rear detector gets pushed, a flight-response is registered. <br>The processing plant uses half ground water, half surface water. The ground water quality is very stable, but surface water quality can fluctuate (especially after heavy rain fall).