Abstract
Herbicides are used to control weeds and are usually targeted to sites that are specific to plants. Butachlor is an herbicide of the acetanilide class, which is widely used in agricultural fields. At the present study, lethal concentration (LC50) of butachlor was calculated for Rutilus rutilus caspicus and Sander lucioperca with a mean weight of 4 ± 1 g (mean ± SD). Our results indicated that LC50 96 h butachlor for R. rutilus caspicus and S. lucioperca were 0.342 and 0.760 ppm respectively. These findings suggest that butachlor is moderately toxic and moderately irritating for these two species. Clinical symptoms included irregular protrusion of the eyes and irregular swimming.