Diplostomum is a taxonomically problematic genus of trematodes, with many members harmful at the metacercarial stage to fish in aquaculture. We found metacercariae eye vitreous humor rudd, Scardinius erythrophthalmus; bleak, Alburnus alburnus; and roach, Rutilus rutilus, Karelia (Russia) identified them as numericum based on combination morphological ecological data. Previously, D. was thought ...