Abstract: An automated biomonitoring system for monitoring water quality includes an exposure chamber for housing an aquatic organism having ventilatory behavior and body movement sensitive to water quality. Electrodes capture electrical signals produced by the organism during its ventilatory behavior and body movement, and a controller responsive to signals from the electrodes determines one or more ventilatory parameters based on the signals. The ventilatory parameters are compared with corresponding thresholds to determine when the water to which the organism is exposed has caused physiological stress to the organism. The signals captured by the electrodes may be corrected for variations in water conductivity so that the signals processed by the controlled are not influenced by conductivity.