Concentrations of As, Cu, Fe, Hg, Pb and Zn and activity concentrations from ^234,238U and ²¹⁰Po in water, fillet, liver and gills were determined in three stocked fish species from the Luis L. Leon reservoir, located in Northern Mexico. The considered species were Lepomis cyanellus, Cyprinus carpio and Ictalurus furcatus. ²³⁸U and ²³⁴U activity concentration (AC) in fillet samples showed values of 0.007–0.014 and 0.01–0.02 Bq∙kg⁻¹ wet weight (ww), respectively. Liver samples for L. cyanellus, C. carpio and I. furcatus present ²¹⁰Po AC of 1.16–3.26, 0.70–1.13 and 0.93–1.37 Bq∙kg⁻¹ ww. Arsenic, mercury and lead concentration intervals in fillet samples were 0.13–0.39, 0.005–0.126 and 0.009–0.08 mg∙kg⁻¹ ww, respectively, while in gill samples they were 0.11–0.43, 0.002–0.039 and 0.02–0.26 mg∙kg⁻¹ ww. The elemental Bioaccumulation Factor (BAF) for fish tissues with respect to their concentrations in water was determined. L. cyanellus showed the highest BAF values for As and total U, being BAF_As = 37 and 40 L∙kg⁻¹ in fillet and gills, respectively, and BAF_{U total} = 1.5 L∙kg⁻¹ in fillet. I. furcatus showed the highest BAF values for Hg and Pb, being BAF_Hg = 40 and 13 L∙kg⁻¹ in fillet and gills, and BAF_Pb = 6.5 and 22 L∙kg⁻¹ in fillet and gills, respectively. Some metal(loid) concentrations are slightly higher than European regulations for fish fillets. The difference in concentrations of metal(loid)s in fillet among the studied species is probably due to their differences in diet and habitat.