This study was designed to determine the concentration of pyrethroids in the environmental media, fish and intestinal parasites with corresponding oxidative stress biomarker response in Epe axis of the Lekki Lagoon, Lagos. Surface water, sediment, fish intestinal samples and the helminth parasite were collected and analyzed for pyrethroids. A total of 125 fish samples were procured. Length ranged from 15cm to 41cm and weight ranged from 36g to 883g. Intestinal samples from infected and non-infected individuals were analyzed for microbial colonization, and anti-oxidants; PRO, SOD, CAT, GSH, MDA and GPx. The three congeners of pyrethroids; Cyfluthrin, β-Cypermethrin and α-Cypermethrin were found in the surface water, sediment and fish but were not detected in the gut parasite. The congener with the highest concentration in surface water was β-Cypermethrin with concentrations of 14.896±6.17ppm but lower than α-Cypermethrin in the sediment. α-Cypermethrin was found in the sediment at the concentration level of 28.129±5.69 ppm, compared to Cyfluthrin and β-Cypermethrin with concentrations of 12.377±4.25 ppm and 14.714±6.38 ppm respectively. The fish intestine had low pyrethroid concentration as compared with the environmental concentrations; Cyfluthrin (1.721±2.61 ppm), β-Cypermethrin (1.411±2.18 ppm) and α-Cypermethrin (0.280±1.32 ppm) respectively. There were low parasitic infections in the fish host with eighteen specimens recorded to be infected with gastrointestinal helminth; Aspidogastrea africanus (trematode) with a prevalence of 34%. There was however higher prevalence of gut microflora (between 30.0% to 40.0%) among individuals infected with the gut trematode. The infected individuals had higher protein, superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH) and glutathione peroxidase (GPx) than the non-infected individuals. Superoxide dismutase (SOD) was the highly most induced; 394.21±48.63 min/mg protein, while catalase was the least induced. Combined effects of parasites and pesticides could induce stress in fish. The histopathological analysis of the infected individuals revealed.