Dead individuals of Chinese mussel Sinanodonta woodiana (Lea) were found in 2009 in the complexof fishponds in Spytkowice (S. Poland) in the Vistula River valley. Earlier records of this invasive alien speciesin Poland come mostly from heated waters. Its occurrence in fishponds indicates that it tolerates also colderwaters; many aquatic ecosystems in Poland may be threatened with its invasion. Endangered swan mussel Anodonta cygnea (Linnaues) was found in the same fishponds. The species had not been reported from thisarea before and it is uncertain whether persistence of its population here is threatened by the invasion of Chinese mussel.