Four species of freshwater fish were included into the research project, namely: pike (Esox lucius L.), zander (Sander lucioperca L.), carp (Cyprinus carpio L.), and bream (Aramis brama L.). Six fish of each species were fished every month from September to November 2007. Morphometric features of fish were assessed as was the content of nutrients and mineral components. Furthermore, a profile of fatty acids was analysed. The content of nutrients in fish depended on the fishing period and its level diminished during the consecutive months of fishing. The highest amount of saturated fatty acids was determined in the fat of bream and pike flesh. The flesh of carp had the lowest level of polyunsaturated fatty acids, whereas the flesh of pike and zander – the highest. From the nutritional point of view, the flesh of pike and zander was characterized by the most beneficial n-3 to n-6 fatty acids ratio. The highest level of EPA was found in the lipids derived from bream and pike, and the fat from pike and zander flesh had the highest level of DHA. The content of heavy metals did not exceed the permissible levels as pointed in relevant standards, and no significant differences depending on the fishing period were found.
fish, nutrients, fatty acids, heavy metals