Vendace, one of the most valued fishes of the Polish lakes, is a species exhibiting substantial phenotypic variability. The comparative morphometric studies were carried out on vendace living in 5 West Pomeranian lakes, Komorze, Pile, Moryńskie, Żerdno and Bytyń. The lakes differ much in morphology. We measured 28 morphometric characters. Statistical analyses revealed a range of significant differences in most of the studied traits among the populations of vendace. In order to find the morphometric traits that are characteristic for a particular lake, we performed a canonical analysis, which revealed that the following traits contributed the most to the discriminant functions: caudal fin length, preocular space length, maxillary length, postdorsal length, and – to a lesser extent – head width. Varied lake environments and morphologies may account for the differences in the fish morphometric characters, since different plankton distribution may require different locomotory behaviour, which has been reflected in the morphological differences.

In the paper there were presented the results of researches on changes of resistances of roach cutting in one year’s cycle, with reference to chemical changes described with content of collagen, fat and water. There was showed the essential influence of collagen, fat and water content on coefficient value of deheading cut work to the total fish mass. Together with increase of collagen and water content, there was increase in lineal accepted coefficient which, instead, decreased with the augmentation of fat content.

The following fishes new on the Polish market were analysed: the Nile perch (Lates niloticus), oilfish (Ruvettus pretiosus, named „butter-fish” in Poland), the African catfish (Clarias gariepinus), and a pangasiid catfish (Pangasius hypophthalmus). Quantitative assays involved protein, fat, fatty acids, fat-soluble vitamins (A, E, D3), macro- and microminerals (calcium, phosphorus, magnesium, selenium, copper), as well contaminants, such as toxic metals (arsenic, mercury, cadmium, lead) and histamine. The fishes are characterised by a varied fat content, low – in relation to Baltic fishes – levels of omega-3 fatty acids, a high content of oleic acid, and a low concentration of toxic metals and histamine.