Impacts of sub-lethal potassium permanganate exposure on endocrine disruption and oxidative stress in Clarias gariepinus

The water in Southern Nigeria is considered unsuitable for immediate consumption due to elevated concentrations of iron and manganese.To remove these metals, a precipitation process involving potassium permanganate (KMnO4) is employed.However, untreated sludge generated during this process becomes hazardous to aquatic environments.This study investigates the effects of KMnO4 on Clarias gariepinus, a prevalent fish species in the region.Fifteen self-bred specimens were exposed to concentrations equivalent to one-tenth of the levels used in water treatment, along with a control group.Fish were sampled at five intervals (days 2, 9, 16, 23, and 30) during the experiment.At each interval, blood samples were collected using anticoagulant-free centrifuge tubes and analyzed for abnormalities in hydrocortisone and superoxide dismutase (SOD) activity.On the 30th day, fish were dissected, and their organs were extracted and analyzed for SOD activity.Spectrophotometry was used to quantify the biomarkers.Results showed marginal upregulation of hydrocortisone secretion and disrupted SOD activity, indicating that critical organs and tissues were unable to mitigate the oxidative stress induced by KMnO4.These findings demonstrate that KMnO4 interferes with endocrine functions and significantly impacts the antioxidant defense system of fish.Consequently, sludge from water treatment facilities must be rendered safe before being discharged into aquatic ecosystems.