Some Pathological Effects of Sub-lethal concentrations of the Methanolic Extracts of Raphia hookeri on Clarias gariepinus

Abstract

Raphia hookeri is a piscicidal plant introduced into inland waterways by artisanal fishermen in Nigeria to 
stupefy fish for easy catch. This study was aimed at evaluating the sub-lethal toxicity of methanol extracts of Raphia hookeri
(MERH) based on histopathological alterations in the gills, liver, kidney, brain and heart of the African catfish (Clarias 
gariepinus) over a 56-day exposure and 56-day post-exposure period respectively. Prolonged exposure resulted in pathological 
changes like erosion of gill filament, thinning of gill lamellae, swollen and oedematous gill filament in the gills and 
centrilobular vacuolar degeneration, kupffer cell hyperplasia and focal necrosis in the liver. Severe widespread tubular 
degeneration, sub-capsular congestion and haemorrhage were also observed in the kidney. Pathological changes like meningeal 
congestion; neuronal degeneration and satellitosis were observed in the brain while hyaline degeneration, epicardial congestion 
and haemorrhage were some of the changes observed in the heart. In view of these findings, the use of R. hookeri extracts in 
harvesting fish by local fishermen in Nigeria should be discouraged until information that aid its application in a sustainable 
manner is made available by further studies.