The habitat requirements of swan mussel Anodonta cygnea L. were studied in water bodies on the floodplain of the Nida river (Southern Poland). Swan mussel showed preferences neither for the geomorphologic types of water bodies nor for natural vs. anthropogenic site origin. It occurred more frequently in wide ponds, with less complicated bank line. Traits of water bodies that were linked with presence of swan mussel correlated also with concentration of dissolved oxygen. Swan mussel avoided silted water bodies and those with high proportion of surface overgrown with floating vegetation. It showed co-occurrence with plants from genus Ceratophyllum L. and Hydrocharis L. It was concluded that preference of the species for larger water bodies, of simpler shape and at early successional stages was related to high oxygen demand in this species. The functioning of natural river valley versus regulated river were discussed in relation to occurrence of large mussel species.