The aim of this study was to estimate the fish quality in terms of the Cu, Fe, Mn and Zn contents. The research material was the muscle tissue of the fish crucian carp (Carassius carassius Linnaeus, 1758), flounder (Platichthys flesus Linnaeus, 1758), Gilthead seabream (Sparus aurata Linnaeus, 1758), mackerel (Scomber scombrus Linnaeus, 1758), Blue grenadier (Macruronus novaezelandiae Hector, 1871), rainbow trout (Oncorhynchus mykiss Walbaum, 1792), tench (Tinca tinca Linnaeus, 1758), tilapia (Oreochromis niloticus Linnaeus, 1758), Walleye pollock (Gadus chalcogrammus Pallas, 1814) and perch (Perca fluviatilis Linnaeus, 1758.). Heavy metals were determined with the atomic absorption spectrometry method (AAS). Significantly high concentrations of zinc (19.52 mg/kg wet weight), copper (0.77 mg/kg) and iron (6.95 mg/kg) were found in the muscles of crucian carp (p < 0.05) compared to the other fish studied, whereas Walleye pollock had a higher content of manganese (0.266 mg/kg) (p < 0.05). All studied fish species do not pose a threat to humans from these four metals. This was indicated by quality indexes (THQ and HI) whose values were below one. The values of these metals also did not exceed the maximum allowable concentrations established by the FAO (1983), but monitoring both the aquatic environment and the fish living there is necessary, for example, for the time-changing abiotic and biotic factors that can cause an increase in metals in the organs of fish.
Keywords: Hazardous Index; Target Hazard Quotient; freshwater fish; heavy metals; marine fish; the combined risk.