Studies on Morphological and Behavioral Alterations of a Freshwater Fish, Labeo rohita Exposed to Tannery Effluents in Ramsar Wetland of West Bengal, India

Tannery effluent was collected from the discharged point to East Kolkata Wetland, a Ramsar site of West Bengal, India, for the purpose of present study. Acute toxicity of the tannery effluent was determined for 96 hours period against Labeo rohita. The LC₅₀ value of effluent was calculated by Finney method (1971). Three sub lethal concentrations 3.53%, 1.76% and 0.88% were selected on the basis of (1/2, 1/4, 1/8) of LC₅₀ value. Various morphological and behavioral alterations were observed in the three sub lethal concentrations for 96 hours. Morphological changes like loosening of scales, sinking of eyeball, redness of eye, profuse mucous secretion, bleeding from gills and hemorrhages were recorded. Behavioral changes consist of gulping of air, opercular movement, erratic swimming, and loss of equilibrium, restlessness and sluggishness. Concentration of 3.53% was found to be highly toxic whereas 1.76% and 0.88% concentrations cannot be overlooked as they also induced alterations in morphology and behavior of fishes. Control fishes were also continuously observed and contrasted with the alterations caused by effluent in each concentration.