Potamon fluviatile northeastern Greece. In mainland Greece, "P. fluviatile" is found in the drainages of the Axios, Thyamis, Aheron and Arachthos, Pineiós, Piros-Tethreas, Pamisos and Evrotas rivers. In the Ionian Islands, "P. fluviatile" is known to occur at only one site on Corfu, as well as on Kefalonia, Lefkada and Zakynthos. In the Aegean Islands, it is found on Skiathos and Skopelos (Sporades), on Euboea and Skyros, and at a single site on Andros in the Cyclades. "Potamon fluviatile" is at the western distributional limit of the genus "Potamon". Other species in the genus occur through Eastern Europe and the Middle East,
Potamon fluviatile and across Central Asia as far east as northwestern India. The populations of "P. fluviatile" on the Peloponnese, Kefalonia, and Zakynthos may represent a separate, cryptic species, and the population from the Peloponnese was described in 2010 as "P. pelops". "P. fluviatile" was formerly divided into three subspecies: "P. f. algeriense", "P. f. berghetripsorum" and "P. f. fluviatile". The first two of these live in North Africa, and were later combined and separated from "P. fluviatile" as the species "Potamon algeriense". By 1983, the nominate subspecies (equivalent to the current circumscription of the species "P. fluviatile") had been divided into