Potamon fluviatile and covers parts of many countries with a Mediterranean coastline. It is found in mainland Italy and on the Balkan Peninsula from Dalmatia to the Axios River in Greece. It is also found on a number of islands, including Sicily, Malta and Gozo, the Ionian Islands, Aegean Islands, Sporades and Andros in the Cyclades. Although the species as a whole is widespread, it is declining in numbers, and these insular populations are particularly vulnerable. "Potamon fluviatile" is widely distributed in much of mainland Italy, especially in the provinces of Trento, Lombardy, Veneto, Liguria, Tuscany, Umbria, Lazio, Campania, Apulia, and Calabria,
Potamon fluviatile are right-handed. In the Tosco-Emilian Apennines, "P. fluviatile" is only found south of the watershed, in contrast with the crayfish "Austropotamobius pallipes", which occurs on both sides on the mountains. Although their ranges overlap, the two species do not inhabit the same water courses, apparently because the crab outcompetes the crayfish, which is therefore forced to live in less favourable locations where the crab cannot survive. Non-indigenous crayfish may pose a greater threat to "P. fluviatile" than native crayfish, although the greatest threats remain pollution, overfishing and the draining of wetlands. The natural range of "Potamon fluviatile" is highly fragmented,