Determination of lethal concentration (LC50-96 hr) of lambda cyhalothrin for a fish, Anabas testudineus (Bloch)

Abstract

The study was conducted to determine the 96-hour LC₅₀ of Lambda-cyhalothrin, a synthetic pyrethroid pesticide, in Anabas testudineus, a freshwater fish species of ecological and commercial significance. Fish were exposed to various concentrations of the pesticide (0.004, 0.005, 0.015, 0.025, 0.035, and 0.045 mg/20L), and mortality was recorded. A clear dose-dependent response was observed. Using probit analysis, the 96-hour LC₅₀ value was calculated to be 0.020 mg/20L. Behavioral changes such as erratic swimming and surfacing were also noted. These findings highlight the high sensitivity of A. testudineus to Lambda-cyhalothrin and emphasize the need for cautious pesticide use near aquatic ecosystems.