Effect of cypermethrin on Heteropneustes fossilis as a predator and its preys branchiura sowerbyiand bellamya bengalensis

Fish and fish food organisms form a trophic cascade, which is constantly exposed to cypermethrin formulations enter in freshwaters. Acute toxicity of the widely-used pyrethroid Cypermethrin formulation (25% EC) on fish-food invertebrates Branchiura sowerbyi and Bellamya bengalensis, and their predator, the Asian stinging catfish Heteropneustes fossilis was studied during present investigation. It was observed that 96 h LC₅₀ values were 0.135, 1.723 and 1.133 μg/l for B. sowerbyi, B. bengalensis and H. fossilis respectively. Clumping tendency in the worms decreased, while that in snails it increased, while fin movement and gill ventilation in the fish decreased due to the treatment of pyrethroid Cypermethrin formulation.