Two alternative hypotheses about aquarium vs fish-farm vectors of non-native distribution of the fish rotan, Perccottus glenii (Odontobutidae), within the Volga River Basin were assessed using a parasitological approach. Three separate locations were studied where rotan populations were assumed to have different introduction histories: (i) vicinities of Tarakanovo pond, Moscow province (aquarium release in 1950), (ii) Ilev fish farm, Nizhniy Novgorod province (unintentional transportation together with stocking of commercial fish in 1970), (iii) the lower Volga River, Saratov province (unknown origin; first record in 1983). The odontobutid-specific tapeworm Nippotaenia mogurndae was the most informative species because it has a complex life cycle and therefore does not persist in aquarium conditions. Absence of this tapeworm in the rotan populations in the first locality and presence in the second location are in agreement with the available information about appropriate vectors of introduction. Populations of rotan in the lower Volga (third locality) where N. mogurndae occurs could originate from individuals unintentionally transported to fish farms together with commercial fish species or have mixed origins. Thus, the presented parasitological data are in agreement with information concerning introduction vectors of P. glenii and confirm that the specific parasite N. mogurndae is a valuable biological tag for analysing vectors and pathways of geographical dispersal of rotan, P. glenii.