Potamon fluviatile crabs' unusual size, up to , and longevity (up to 15 years) are also interpreted as evidence of a long-established population, by analogy with island gigantism. On the island of Malta, "Potamon fluviatile" is rare and restricted to a few locations in the west of the island. On Gozo, there is a single population which inhabits a stretch of river only long. In the Balkan Peninsula, "Potamon fluviatile" is known to occur in Croatia, Montenegro, the Republic of Macedonia, Albania and Greece. There are four species of "Potamon" in the Balkans, and "P. fluviatile" is replaced by "Potamon ibericum" in
Potamon fluviatile "P. fluviatile", but a number of animals take it opportunistically, including rats, foxes, weasels, birds of prey and jays. The most significant predator may be mankind, with individual prospectors able to catch 3,000 to 10,000 in one season. Adults occupy burrows, while smaller individuals shelter under stones. The entrances to the burrows may be more than from the stream's edge and are always above water level. The burrows may be more than long, and probably serve to protect the crabs from extreme cold. "Potamon fluviatile" is an aggressive species, mostly attacking with the larger right claw, since 90% of individuals