Evaluation of Oxidative Stress and Histological Changes Caused by a Common Laundry Detergent in the Freshwater Fish, Channa punctatus

Abstract

Laundry detergents, with their pervasive domestic and industrial use, introduce chemically complex effluents into aquatic systems, where many components demonstrate significant toxicity to aquatic life. This study investigated the sublethal effects of a commercially prevalent detergent, Ariel, on the freshwater fish Channa punctatus, focusing on histopathological alterations and oxidative stress biomarkers in liver and gill tissues. The median lethal concentration (LC₅₀) for 96 hours was determined to be 32 ppm via probit analysis. To assess chronic toxicity, fish were exposed to a sublethal concentration (6.4 ppm, one-fifth of the LC₅₀) for 7 and 14 days. A significant (p<0.05) time-dependent decline was observed in the activities of key antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione-S-transferase (GST), and in glutathione (GSH) levels in both tissues. Concurrently, xanthine oxidase (XO) activity and malondialdehyde (MDA) levels, an indicator of lipid peroxidation, were markedly elevated. Histological examination revealed pronounced impairments, including disorganized and degenerated hepatocytes, sinusoidal dilation, and vacuolization in the liver. Gill tissues exhibited hyperemia, congestion in the secondary lamellae, and, after 14 days, curling and fusion of lamellae. The toxicological perturbations were more severe in the 14-day exposure group and consistently more pronounced in gill tissue compared to liver. These findings demonstrate that Ariel detergent induces significant oxidative stress, leading to time-dependent histopathological damage, likely due to the synergistic action of its chemical constituents, highlighting a substantial ecotoxicological risk to freshwater fish.