Red-clawed Crab

Perisesarma bidens, the Red-clawed Crab, is a mangrove-associated sesarmid crab widespread across the Indo-Pacific, where it inhabits the complex root systems and mudflats of mangrove forests. It is characterised by a dark brown-black carapace and brilliantly red chelae that give it an immediate visual appeal in paludarium setups. It is one of the most commonly available mangrove-associated crabs in the hobby.

This species requires access to both land and brackish water to thrive. Fully freshwater conditions will lead to osmotic stress and shortened lifespan, while fully terrestrial conditions without water access are equally unsuitable. A well-designed paludarium with a shallow brackish tidal zone, exposed root structures for climbing, and soft substrate for burrowing represents ideal husbandry.

P. bidens is omnivorous and will consume detritus, algae, plant matter, and small invertebrates. It is not safe with small fish or shrimp in the water section of a paludarium. Males are somewhat territorial and will posture at each other, but low-level combat in a well-spaced setup is generally tolerated.

Water: 22–28°C, pH 7.5–8.5, SG 1.005–1.015 brackish; access to land essential. Tank: minimum 40 L paludarium with mangrove-style roots, shallow brackish zone, muddy substrate. Feeding: omnivore — algae wafers, dried shrimp, blanched greens, detritus, micro pellets. Breeding: larvae are marine and require seawater — captive breeding not practical in standard setups. Compatibility: not safe with small fish or shrimp; keep with conspecifics in appropriately sized paludarium.