Responses and Histopathological Studies of Clarias gariepinus Exposed to Selenium Toxicity

Abstract

Various toxicants have been deposited into aquatic environment due to human activities, in light with this, 180 healthy Clarias gariepinus juveniles with mean weight of 7.4±0.64 g and length of 11.2±0.88 cm were exposed to different concentrations of selenium (a typical toxicant) to evaluate its behaviour and histopathological response. The fish were exposed to different concentrations (2, 3, 4, 5 and 6 mg/L) of selenium under a static bioassay for 96 hours after a range finding test and 96 hours LC 50 was determined using probit method. 10 fish per concentration was used for the bioassay in triplicates. The 96 hours lethal concentration (LC 50 ) was estimated to be 3.39 mg/L. The histological examination of the gill revealed hyperplasia and haemorrhage of the gill lamellar. The kidney showed vacuolation and blood stains while the skin demonstrated mucosal eruption. These alterations increase with increase in selenium concentration. Selenium at high concentration has shown to induce behavioural changes on fish and also alterations to organs of C gariepinus juvenile. It is therefore recommended that industries ensure the incorporation of effluents treatment plants to treat wastes before discharging into the environment.