European River Crab Potamon fluviatile

Potamon fluviatile is the primary freshwater crab of the Mediterranean region, native to rivers, streams, and lake margins across southern Europe including Italy, the Balkans, Greece, and adjacent areas. It is one of the few freshwater crabs endemic to Europe and holds protected status in several countries due to habitat loss and water quality degradation.

This species is fully aquatic, rarely leaving the water except during nocturnal dispersal in wet conditions. Its broad, smooth carapace is olive-green to dark brown, and adults develop substantial, powerful chelae capable of crushing snail shells and woody debris. It is a fast and agile species in the water.

In captivity, P. fluviatile requires cool, clean, well-oxygenated water — characteristic of the Mediterranean streams it inhabits. It is territorial and should be kept individually or in very spacious aquaria with multiple separated rocky territories. It will prey on all invertebrates and small fish housed with it. A secure lid is essential. This is a species for dedicated keepers who appreciate the significance of Europe's only native freshwater crab.

Water: 16–22°C, pH 7.0–8.0, GH 6–18, KH 3–12; cool, clean, well-oxygenated; high-turnover filtration essential. Tank: minimum 80 L; rocky caves and overhangs, coarse gravel, cool water; unheated in temperate rooms; secure lid. Feeding: omnivore — sinking pellets, frozen bloodworm, mussel, snails, blanched vegetables; feed every 1–2 days. Breeding: direct developer; female broods large eggs; fully formed juveniles; cool stable conditions required. Compatibility: one per tank; predatory on invertebrates and small fish; territorial; European biotope setups only.