Biomonitoring: cadmium deteriorates electro-orientation performance in catfish.

1. Exposure of catfish, Ictalurus nebulosus, to sublethal concentrations of cadmium deteriorates electro-orientation performance. 2. Cadmium, at a concentration of 40 micrograms/l, doubles the behavioural threshold for electric stimuli within 48 hr of exposure; both prolonged exposure and higher concentrations result in higher thresholds. The effect is reversible. 3. Electro-orientation performance can be used to monitor the quality of surface water.