The acute toxicity of copper cyanide to the juveniles of Indian major carp Catla catla (2±0.5 cm) was evaluated under static renewal conditions. The concentrations of copper cyanide that killed 50% of the carp fingerlings within 96-h (96-h LC50) was found to be 0.76 ± 0.04 mg/L. Fishes exhibited abnormal swimming activity, followed by frequent gill flapping, loss of equilibrium, gulping of air, hyperactivity, convolutions. The respiratory rate of the fish got severely affected (-63.41%± 0.002) when exposed to copper cyanide.
