The ecotoxicology of Hg was investigated by determining Hg levels in capelin (Mallotus villosus), redfish (Sebastes sp.), and haddock (Melanogrammus aeglefinus). For redfish and capelin, total Hg concentrations were different in the three different water masses (Arctic water, Atlantic water, and mixed Polar front water). For all three species fish length was correlated with total Hg concentration. The relative concentration of organic Hg varied between 11 and > 100%. The concentration of Hg found in Barents Sea fish was proposed as close to background levels.