Some biological and hematological responses of Oreochromis niloticus juveniles exposed to Atrazine herbicide

This research was aimed at finding the influence of Atrazine on a most widely farmed fish,Oreochromis niloticus (Linnaeus, 1758), in Nigeria. Specific areas of investigation were to find the LC50after 24, 48, 72 and 96 hours of the chemical administration to the fish. The effects of the chemical onthe behavioral and biological responses of O. niloticus were equally observed. The ten fish each werestocked in six different tanks containing 40 liters of water. These tanks contained graded concentrationsof the chemical and the treatments were replicated three times. Dissolved oxygen content was reducingwith increasing Atrazine concentration, while temperature and pH increased with increasing Atrazineconcentration. The LC50 of Atrazine in 24, 48, 72 and 96 hours were 7.9, 7.6, 7.3 and 7.2 respectively.Behavioral and biological responses included loss of reflex, air gulping, erratic swimming, discoloration,hemorrhage and molting. The blood parameters observed showed that there were increases in packedcell volume (PCV) and red blood cell count (RBC) and decrease in hemoglobin (Hb), erythrocytesedimentation rate (ESR) and mean cell hemoglobin (MCH), while there was no significant change inwhite blood cell count (WBC) and mean cell volume (MCV) values. The chemical was therefore observedto be lethal to juvenile O. niloticus.