iarjalsIARJALSIARJALS2708-5104https://doi.org/10.47310/iarjals.2021.v02i01.034Changes in Antioxidant Levels in Two Sizes of Tilapia guineensis Exposed to Atrazine in the LaboratoryUkazuE.RUzoaluI.AFish Technology Department, Nigerian Institute for Oceanography and Marine Research, Wilmot Point Road, Victoria Island, PMB 12729, Lagos – NigeriaChanges in the activities of some antioxidants which include catalase (CAT), Superoxide dismutase (SOD), Lipid peroxidase (LPO) and Glutathione (GSH) in the plasma of Tilapia guineensis treated with Atrazine were evaluated spectrophotometrically to assess the level of oxidative stress in fish exposed to the chemical.  Blood samples were collected from juveniles and adult’s sizes of T. guineensis and were analyzed with Randox test kits. Results from the antioxidants analysis showed that the values of SOD and GSH reduced significantly (p<0.05), while CAT and LPO increased in both sizes when compared to the control. These alterations were concentration dependent and more critical in the juvenile than the adult fish.