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.
Keywords: Clarias gariepinus; Hydrocortisone; Metals; Potassium permanganate;
Superoxide Dismutase