Anguillicola crassus infection of paratenic hosts was investigated in Lake Velence, Hungary, in October 1992. A total of 155 specimens of 8 species (Gymnocephalus cernuus, Lepomis gibbosus, Stizostedion lucioperca, Abramis brama, Alburnus alburnus, Cyprinus carpio, Pseudorasbora parva and Rutilus rutilus) were examined: all species proved to be infected. There were large differences in the prevalence of infection among fishes, but the prevalence was generally higher in Perciform fishes and it was the highest in G. cernuus (100%). The occurrence and physical stage of larvae did not depend on the size of the fish. In S. lucioperca the size of third stage larvae was bigger than in other fishes, and only live larvae were found. The comparison of Lake Velence and Lake Balaton indicates that the rate of larval infection in paratenic hosts of A. crassus is higher in Lake Velence. This might be explained by the significant ecological differences between the two lakes (population of intermediate hosts, water depth, salinity, pH).