The aquatic invader Potamopyrgus antipodarum (Gray, 1843) is a poorer food item for benthivorous fishes than native snails.
Laboratory experiments have indicated that tench (Tinca tinca) is an effective predator of Potamopyrgus antipodarum. However, few P. antipodarum have been found in the gastrointestinal tracts of wild caught benthivorous fishes, including tench. This had led to the assumption that the shell properties of the snail act against native predators. In general, it has been predicted that this is due to P. antipodarum possessing a thicker shell and a lower amount of soft tissues than native snails; the latter will thus be preferred by benthivorous fishes. In the current study, shellcrushing resistance and the soft tissue mass/shell mass ratio were compared between the non-native P. antipodarum and three native species. Results indicated a similar shell-crushing resistance for P. antipodarum relative to the native Bithynia tentaculata, the latter of which is a common food object in tench diet. However, the soft tissue mass/shell mass ratio of the invader was significantly lower than in most of the studied native snails, indicating a lower amount of soft tissues in P. antipodarum.