Abstract
Two species of weakly electric fish, Gnathonemus petersi and G. tamandua (Family Mormyridae), have been exposed to differing concentrations of atrazine, atrazine in the presence of cyanide and lindane. Significant responses to concentrations of 0.1 mgl‐1 and 0.05 mgl‐1 of both compounds were measured as modification of the electric organ discharge (EOD) rate. Applications of 0.05 mgl‐1 atrazine plus 0.1 mgl‐1 cyanide have a synergistic effect on sensitivity of response.