Acute toxicity of industrial effluent on the marine catfish Arius nenga (Hamilton, 1822)

Industrial effluents, controversially, is one of the largest and major contributors of pollution in aquatic ecosystem and affects the aquatic organisms in general and fishes in particular. Several laboratory studies were conducted to evaluate the effects of both treated and untreated effluents on fish. The studies showed wide ranges of toxicity at organismal as well as at population levels. The present work deals with the determination of acute toxicity of Kerala Minerals and Metals Limited industrial effluent on the marine catfish Arius nenga. The effluent was highly acidic and contains a battery of heavy metals. Static bioassays were performed on, A. nenga to evaluate the median lethal concentrations of industrial effluent. Mortality increased as the concentration of effluent increased and 5.8% of effluent was obtained as 24 h LC50. The work eventually revealed that the KMML industrial effluent has a high level of toxicity to marine catfish. Harmful effects such as biomagnification and other aberrations may occur in man if exposed to substantial concentration of the effluent.