Understanding the Impact of Sodium Metabisulfite (Na2S2O5) Exposure on Soft Tissues (Gill, Kidney and Liver) of Freshwater Fish Labeo rohita

Background: Sodium metabisulfite (Na2S2O5) is a disinfectant and preservative agent which is commonly used in food industry and polluted water bodies through industrial wastes. Objective: Current study was conducted to observe the impact of widely used salt on the gills, kidney and liver of Labeo rohita. Methods: Fish were divided into three groups. One group treated as control. Two groups were exposed to sodium metabisulfite in different concentrations (29 mg/L and 68 mg/L) for 28 days. Results: The 96h LC50 value for sodium metabisulfite (Na2S2O5) was found to be 130 mg/L. Histological changes revealed moderate to severe damage in time and concentration dependent manners. Photomicrograph of gills of exposed fish showed different histological alterations such as hyperplasia, marginal gill lamellae, blood congestion, gills lamellae aneurysm and distortion of the gill cells. Results indicated that exposure to sodium metabisulfite caused severe progressive alterations such as melanomacrophage, cytoplasmic vacuolization, hepatocytes and cluster nuclei in liver tissues of exposed fish. Kidney tissues of treated L. rohita revealed different histological changes including, wide hypertrophied nucleus, sinusoidal spaces, cloudy swelling degeneration, glomerular expansion and tubules starting the degeneration process as compared with control fish. Conclusion: Our results represent the pioneering report demonstrating that sodium metabisulfite can act as a potent toxic agent for Labeo rohita.