The lumpsucker (Cyclopterus lumpus Linnaeus, 1758) is a marine fish inhabiting shallow coastal areas of North Atlantic. In 1996-2006, 224 lumpsucker individuals caught in the Gulf of Gdańsk and Vistula Lagoon (Poland) were examined for metazoan parasites. The fish were found to support the cestode Eubothrium crassum (Bloch, 1779), the nematodes Contracaecum osculatum (Rudolphi, 1802) L3, Dichelyne minutus (Rudolphi, 1819), and Hysterothylacium aduncum (Rudolphi, 1802) L3, L4, ad. as well as the acanthocephalans Corynosoma strumosum (Rudolphi, 1802) cyst., Echinorhynchus gadi Zoega in Müller, 1776, and Pomphorhynchus laevis (Müller, 1776). The total (both areas) prevalence of parasites was 63.4% at a mean intensity of 2.1 inds. In the Gulf of Gdańsk, 66.3% of all the lumpsucker examined were infected (intensity 2 inds), the level of infection in the Vistula Lagoon being 46.5% of the fish (intensity 2.3 inds). The Gulf of Gdańsk lumpsucker supported all the parasitic species listed, while 4 species only (E. crassum, H. aduncum, E. gadi, and P. laevis) were recorded in the Vistula Lagoon. The dominant parasites were H. aduncum (43.3%, 2.1 inds) and E. gadi (21.0%, 1.2 inds). All the parasitic species, except C. strumosum, are being reported from the southern Baltic lumpsucker for the first time.
