Toxicological effects of dichlorvos on haematology and histological changes in <i>Clarias gariepinus</i> juveniles and ameliorative potentials of <i>Moringa oleifera</i> leaves

Abstract

The presence of Dichlorvos in aquatic environment posed potential toxic effects on fish. Effects of Dichlorvos and ameliorative potential of Moringa oleifera leaves on Clarias gariepinus juveniles was investigated. The fish were exposed to varying concentrations (0.00, 0.50, 0.75, 1.00, 1.50 and 2.00 mg/l) of Dichlorvos for 96 h, 1/10th of 96 h LC₅₀ (1.75 mg/L) and fed on M. oleifera leaves (0, 5 and 10%) for 28 days. After the experiments, blood of the fish was assayed for haematological variables, while gills and liver were assayed for histopathological damages. The levels of erythrocytes and leucocytes in the exposed groups decreased (P <0.05) and increased (P<0.05) respectively compared to control, but, elevated and reduced significantly (P<0.05) in fish fed on 5% M. oleifera leaf respectively. Histopathological alterations such as lamellar fusion, oedema and necrosis were observed in the gills, while vacuolation, fibrosis, and necrosiswere revealed in the liver of Dichlorvos-exposed fish compared to control. However, the severity of damage reduced in the group fed on 5 % M. oleifera leaves. These results imply that 5% M. oleifera leaves in fish feed is capable of ameliorating the toxic effects of Dichlorvos on C. gariepinus.

Key Words: Amelioration, Dichlorvos, haematology, histology, Moringa oleifera leaves