Taiwanese Freshwater Crab Geothelphusa dehaani

Geothelphusa dehaani is Taiwan's most widespread freshwater crab, inhabiting mountain streams, rivers, and rocky hillside water bodies across the island. It is a medium-sized, smooth-shelled species with a broad, flattened carapace in olive-green to warm brown tones and moderate chelae. As a highland and mid-altitude species, it is adapted to cooler water temperatures than most tropical aquarium crabs.

In captivity, G. dehaani is fully aquatic and adapts well to appropriately sized freshwater aquaria provided with rocky structure, caves, and clean water. It is territorial and should generally be kept individually unless a very large aquarium allows for separated territories. Aquaria do not need to be heated in temperate climates — in fact, the species tends to be stressed by temperatures consistently above 24°C.

G. dehaani is an omnivore accepting a wide range of sinking foods and occasional plant material. It is more tolerant of neutral pH and moderately hard water than many freshwater crabs. Breeding in captivity is possible: females brood eggs directly and release fully formed juveniles, bypassing any larval stage. This direct-development strategy simplifies captive breeding considerably.

Water: 16–24°C, pH 6.8–7.8, GH 5–15, KH 2–10; clean, well-oxygenated; cooler temperatures preferred. Tank: minimum 60 L; rocky caves and crevices, fine gravel, good flow; unheated or lightly heated in temperate rooms. Feeding: omnivore — sinking pellets, frozen bloodworm, blanched vegetables, dried shrimp; feed every 1–2 days. Breeding: direct developer; female broods eggs; releases fully formed miniature juveniles; no larval stage. Compatibility: one per tank unless very large; fully aquatic; predatory on invertebrates; keep with robust fish only.