Physicochemical Characteristics of Fertilizer Industry Effluent and its Toxicological Impact on the Activity of Acetylcholinesterase (AChE) in Freshwater Teleosts Heteropneustes fossilis and Labeo rohita

Industrial revolution is a good indicator of economic development of a country; however, it can be a threat to the flora and fauna if the untreated effluent of an industry is discharged. The present study is aimed to assess the comparative toxicological impacts of treated and untreated industrial effluents on acetylcholinesterase (AChE) activity in Heteropneustes fossilis and Labeo rohita, the most common edible fishes having diverse characters which include differences in morphology, habitat, food and feeding, etc. The physico-chemical parameters such as pH, electrical conductivity (EC), alkalinity, hardness, dissolved oxygen (DO), phosphate, sulphate, nitrate, free ammonia, chloride, zinc, iron, chromium and potassium of both untreated and treated effluent from the fertilizer industry were also analyzed as these parameters were not in range as per ISO guidelines. The LC₅₀ value for untreated effluent was 2.34% (v/v) and 0.80% (v/v) for 96 h in H. fossilis and L. rohita, respectively, while no mortality was recorded in the treated effluent. The AChE activity in both fish species was found to decline in metabolically responsive organs like brain, muscle and gills through exposure to sub-lethal concentrations (1/15^th, 1/10^th and 1/5^th of LC₅₀ value) of the untreated effluent for 96 h. Further studies on biochemical and molecular aspects may reveal the mechanism of their action.