biomonitoring is a practice that has over time developed into a remarkably accurate form of detecting toxicity in the environment. the toxicity early warning system (tew) is a real-time biomonitoring system developed to monitor the toxicity of industrial effluent to rainbow trout (oncorhynchus mykiss) prior to the effluent entering into the environment. the development of a trout behavioural-response-to-toxicity library can eventually be used to monitor and prevent toxic industrial spills. in the tew tests trout were exposed to three pulp and paper effluents (kraft, news and kraft clean water outfall). the tew test is a 12hr test, consisting of an acclimation period and an effluent exposure period which runs off of an inexpensive, conductivity bridge circuit. trout behavior was obtained via an oscillating signals produced by the conductivity bridge circuit. this signal was statistically analyzed using a single factor anova, averages, and coefficient of variance. results show that the normal ventilatory patterns of rainbow trout averaged between a range of 0.013 8v - 0.7895v in ventilatory depth and 2- 4 breaths per second. general activity was monitored as whole body movement (fin and body action). trout on average were active and sporadic in their movement, averaging 2.39v during the acclimation periods. exposure to kraft effluent resulted in severely reduced body movement at all concentrations, breathing patterns declined to an almost consistent 2.0v ventilatory depth, with a cyclical 2.0v - 3.5v ventilatory frequency. exposure to news effluent resulted in increased body movement, decreased ventilatory depth (0.0470v) and ventilatory rate (1.47 breaths per second). there were no significant behavioral results exhibited when trout were exposed to kcwo.