Effects of sodium arsenite on the behaviour of the freshwater stinging Catfish, Heteropneustes fossilis

Abstract

Toxic metals usually accumulate in the environment due to human activities. Although arsenic, along with its compounds, is a notably potent natural contaminant of groundwater, human activities such as mining, smelting, burning of fossil fuels, use of arsenic-based pesticides and industrial waste contribute significantly. Arsenite (As3+) and arsenate (As5+) are considered the most toxic and prevalent arsenicals found in nature. In the present study, experiments were conducted to evaluate the acute toxicity of sodium arsenite on the freshwater catfish, Heteropneustes fossilis, over 24-hour and 96-hour periods. Fishes were divided into control and treatment groups 1 and 2, each with 10 fishes of nearly equal size and weight. Fishes of both treatment groups 1 and 2 were exposed to sodium arsenite (1 mg/L, purity 99%, Sigma-Aldrich) for 24 hrs and 96 hrs, respectively, with a water change for treatment group 2 for four consecutive days. Both the control and treated groups of fish were observed for behavioural changes after 24 hours and 96 hours. The results indicated that exposure to sodium arsenite induced erratic movement, hyperexcitability, and excessive mucus secretion from the gills and body surfaces. Additionally, the fishes also exhibited signs of agitation, rapid opercular movement, occasional air gulping, and ultimately losing their equilibrium showing clear signs of distress due to the arsenic exposure. This study highlights the severe behavioural impacts of arsenic contamination on aquatic life, emphasizing the need for effective management of such pollutants in aquatic ecosystems.