The aim of this work was to analyze the concentrations of select elements such as sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn) in the water, muscle tissue, and gills of perch sampled in autumn from Lake Gopło in NW Poland. The correlations between the fish size (body length) and metal concentrations in the tissues were investigated by linear regression analysis. In addition, the bioaccumulation coefficient, as a measure of accumulation intensity of an element in an organ, was analyzed. The mean content of K, Mg, and Zn in the analyzed perch was higher in the muscle (18.90, 1.53, and 52.92, mg·kg^-1) than in gills (8.88, 1.30, and 44.99 mg·kg^-1), and the difference between these values (except for Zn) was statistically significant (p≤0.05). The analyses of the correlation between metal concentration in the meat and the body length of fish show that the bioaccumulation of Na, K, Mg, and Zn decreases as fish body length increases (negative correlation). The evaluation of the chemical pollution of Lake Gopło concentrations was based on the following ions (N-NO₃, N-NO₂, and P-PO₄) and minerals (Na, K, Ca, Mg, and Zn). The concentrations of nitrite nitrogen in the waters of Lake Gopło range from 0.012 (in September) to 0.057 mg N-NO₂ dm^-3 (in November). The concentration of nitrate nitrogen ranges from 0.09 to 1.888 mg N-NO₃ dm^-3. The concentration of orthophosphate in surface waters of Lake Gopło is not very diverse (0.17-0.2 mg PO₄ ^-3 dm^-3).