Abstract

The aim of present study was to determine the LC₅₀ value of in Caspian sea kutum. The results indicated that median lethal concentration (LC₅₀) of Caspian sea kutum (Rutilus frisii kutum) for 24, 48, 72 and 96 h of exposure are 2.944, 2.756, 2.562 and 2.310 ppm, respectively and median lethal concentration (LC₅₀) of lead to Caspian sea kutum (R. frisii kutum) for 24, 48, 72 and 96 h of exposure as 315.841, 298.456, 281.419 and 268.065 ppm, respectively. LC₅₀ increased with decrease in mean exposure times for both metals. Physiological responses like rapid opercular movement and frequent gulping of air was observed during the initial stages of exposure after which it became occasional. All these observations can be considered to monitor the quality of aquatic ecosystem and severity of pollution. Hence, concluded that copper is more toxic than lead for Caspian sea kutum (R. frisii kutum).

Key words: Copper sulfate, lead nitrate, Rutilus frisii kutum, Caspian sea kutum, physiological responses, median lethal concentration (LC₅₀).