iarjasfrIARJASFRIARJASFR2789-598Xhttps://doi.org/10.47310/iarjasfr.2021.v01i01.011Changes in Lymphocytes in Three Sizes of African Catfish (Clarias gariepinus) Exposed to Different Chemicals in the LaboratoryAkinrotimiO.AWilfredEkprikpo P.C.UkweO.I.KAfrican Regional Aquaculture Center/Nigerian Institute for Oceanography and Marine Research, Buguma, Pmb 5122, Port Harcourt, Rivers State, NigeriaAquaculture Department, Nigerian Institute for Oceanography and Marine Research, 3, Wilmot Point Road, Victoria Island, PMB 12729, Lagos - NigeriaDepartment of Fisheries and Aquatic Environment, Faculty of Agriculture, Rivers State University, Nkpolu-Oroworukwo, Port Harcourt, Rivers State, NigeriaChanges in the number of  lymphocytes in the blood of three sizes of Clarias gariepinus exposed to three pesticides paraquat dichloride (PARAQ), 2,2-dichlorovinyl phosphate (DDVP) and dimethoate (DMC) at the concentrations of 0.00 control, 1.00, 2.00, 3.00 and 4.00 mg/L were carried out. The result obtained indicated a concentration dependent increase which was more pronounced in the fish exposed to   paraquat dichloride, followed by DDVP, while the lowest effect was observed in the fish exposed to dimethoate in all sizes of the fish. The result revealed that paraquat was more toxic to the fish, causing more stress as indicated through elevation of the lymphocytes in the blood stream of the fish.