TOXICITY OF AQUEOUS EXTRACTS OF Vernoniaamygdalina LEAVES TO AFRICAN CATFISH ( Clariasgariepinus ) JUVENILES

Abstract

The study evaluated the toxic effects of Vernoniaamygdalina (bitter leaf) on Clariasgariepenusblood profile, gills, liver and kidney as biomarkers of environmental quality in toxicity testing of aqueous extracts of bitter leaf using the standard method of the American Society for Testing and Materials (ASTM) . One hundred and eighty apparently healthy juveniles of C. gariepinus (17.05 ± 0.25g) were randomly distributed into eighteen bioassay tanks (20L) with stocking density of ten (10) fish per tank. A range finding test was conducted prior to the experiment. The fish were later exposed to 0ml (contol), 40ml, 45ml, 50ml, 55ml, and 60ml per litre concentrations of aqueous extracts of V.amygdalina for 96hrs in a static bioassay procedure. Erratic swimming, loss of equilibrium, respiratory disturbance, lethargies and mortality were observed in the exposed fish which increased with increasing concentration of plant extract. Differences observed in the mortalities of C.gariepenus at varying concentrations were significant (P < 0.05). The control experimental fish neither died nor exhibited any unusual behavior. The LC50 for C.gariepenus juveniles exposed to aqueous extract of V.amygdalina for 96hrs was 53.517ml/l. The results of hematological parameters indicated a significant (P < 0.05) decreasing trend in the red blood cell, haemoglobin and the packed cell volume with increasing concentrations of V.amygdalina while the leucocyte counts increased with increasing concentrations of V.amydgalina. Highest haemoglobin value (12.40±0.30) was recorded for the control while the lowest (9.05±0.25) was recorded in fish exposed to 60ml/l V.amygdalina. The control had the lowest (3.07±0.20) leucocyte counts while the highest count (6.13±1.21) was recorded in fish exposed to 60ml/l V. amydgalinaaqeous extract.The gill histological changes observed were lesion and vacoulations, severe erosion of