The dissertation is targeted on determination of structure of parasites communities of the invasive goby-like fishes (Actinopterygii: Gobiiformes), e.g. monkey goby (Neogobius fluviatilis), round goby (Neogobius melanostomus), racer goby (Babka gymnotrachelus), western tubenose goby (Proterorhinus semilunaris) and Chinese sleeper (Perccottus glenii), at different stages of invasion. The aim of the study was to describe the processes of parasite community forming in populations of invasive fish in places of introduction, in the view on the modern concepts and hypotheses in invasion theory. During the study, the species compositions of parasite communities of the different gobiiform fish in the invasive ranges in Europe and North America were detected. The data on the parasite fauna of the invasive gobies in the Baltic Sea, Vistula and Elbe drainages, Lake Erie and Lake Huron drainages are reported for the first time. Also, we presented for the first time the parasite fauna of the Chinese sleeper in Ukrainian and Polish bodies of water. The taxonomic position of several parasite species (with unclear or discussible status) was clarified. We determined the taxonomic status of the microsporidians from the gut wall of the Ponto-Caspian gobies and of the cyathocotylid metacercariae from the internal organs of gobies. The round goby is reported as the host of several parasite species for the first time, e.g. monogenean Gyrodactylus rugiensis, trematode Neochasmus umbellus, acanthocephalans Neoechinorhynchus tumidus and Acanthocephalus rhinensis, nematode Anguillicola crassus, leech Piscicola geometra, also mites Hydrachna sp. and Unionicola sp. The western tubenose goby is reported as a new host for two parasites: trematode Cyathocotyle prussica and acanthocephalan Southwellina hispida. The parasites, such as monogenean Gyrodactylus luciopercae, trematode Schiginella colymbi, acanthocephalans Acanthocephalus anguillae, Acanthocephalus and Pomphorhynchus laevis, occurred in the Chinese sleeper for the first time. The cestode Nippotaenia perccotti was reported for the fauna of Ukraine for the first time, but the metacercariae Diplostomum gobiorum were first found in Poland. We provide the first registration of monogenean Gyrodactylus perccotti in the Danube Delta and of metacercariae Holostephanus cobitidis and Holostephanus luhei in the Middle Vistula, also acanthocephalan A. rhinensis in the Lower Elbe. Among other, during the field works, the Chinese sleeper was first registered in the Southern Bug drainage (Hirskyi Tikych River), Dnieper Estuary and the Ukrainian part of the Danube delta. The infestation of the invasive gobiiform fishes with different macroparasite life stages, as well as the percentage of the endo- and ectoparasites were determined. The processes of the gobiiforms' parasite communities forming in the particular corridors of invasions, also in the cases of Transbaltic and Transatlantic invasions, are explained. We report the influence of the dams of Wloclawek Reservoir (Vistula River) and Geesthacht weir (Elbe River) on the distribution of the invasive gobies via European corridors of invasions. The affect of the external and internal factors on the parasite communities of the sympatric and isolated gobiiforms populations is described. The relationships between the forming of gobiiforms parasite communities and local fauna are discovered. The role of the invasive gobiiform fishes in the parasites life cycles in the invaded ecosystems is described. The invasion success of the gobiiform fishes is explained with regard to main invasion hypotheses and concepts in the biological invasion theory. The processes of colonisation of the gobiiformes by parasites along the invasion corridors are present for the first time. We first reported the low parasite load on the invasive gobiiform fishes, as the support for the "enemy release hypothesis". We described the colonisation of the Ponto-Caspian gobies by parasites along the Central Corridor of Invasions and discovered the trend to accumulation of acquired parasites by gobies along this corridor. The risk of the spread of new parasite species with the invasive gobiiform fishes in the invasive range was detected. The role of the invasive gobies in the distribution of the non-native parasite species, which were introduced with the other then gobies vectors, are described.
