The invasion of Ponto-Caspian taxa in Western Europe has increased steadily since the connection of the Danube basin with the R hine basin in 1992, in combination with transfers through interbasin shipping. In 2010, the tubenose goby ( Proterorhinus semilunaris ) and round goby ( Neogobius melanostomus ) were observed in Belgium for the first time. To gain insight in the introduction pa thways in Belgium and to identify potential source populations, a phyl ogeographical and parasitological study was initiated on both species. The mitocho ndrial cytochrome b gene was sequenced, its haplotype diversity calculated and a statistical parsimony haplotyp e network built. Both species exhibited low haplotype diversity compared to native and ot her non-native populations. The netw ork revealed potential source lo cations in the Northern Black Sea for the round goby and in the Danube at the Serbian-Romanian border for the tubenose goby. Fins, gills a nd body were examined for the presence of ectoparasites. Prevalence, abundance and infection intensity was much higher in tubenose goby , which might be the consequence of a different in troduction pathway. Our data provides evidence that tubenose goby entered Belgium thr ough active dispersal. The round goby, however, was mo st likely introduced with ballast water.