Freshwater Crabs for Aquarium Complete Guide: 8 Species
Most “freshwater” crabs sold in the trade are not fully aquatic — they drown without dry land or climb out of open tanks at night. This freshwater crabs for aquarium complete guide from Gensou Aquascaping at 5 Everton Park breaks down eight species by habitat type (paludarium, aquatic, brackish), adult size, temperament and Singapore availability. Buying a crab without knowing which category it falls in leads to escapes, deaths and surprise NParks permit questions. A little research up front solves all three.
The Three Habitat Categories
Land-biased crabs need 70-80 percent dry area with shallow water dishes — vampire, halloween and red-apple fit here. Fully aquatic crabs live submerged — Thai micro and pom-pom. Brackish-water crabs sit in between, needing salt and occasional land access — red-claw and fiddler crabs belong here. Matching setup to species is the single biggest care decision. The tanks and cabinets category includes paludarium-ready setups.
Vampire Crab (Geosesarma species)
The Instagram darling. Purple-bodied with yellow eyes, growing to 2.5-3 cm carapace. Strictly a land climber needing 80 percent dry area with moss, cork bark and a shallow 2 cm water dish. Drowns in aquarium setups. Humidity 70-85 percent, 24-28 °C. Carousell morphs run SGD 15-40 each depending on colour. Occasionally at C328 and specialist reptile-crossover shops. Keeps in small groups in 40×30 cm paludariums.
Thai Micro Crab (Limnopilos naiyanetri)
The only fully aquatic crab on this list. Tiny at 1 cm across, completely peaceful, breeds in freshwater. Lives in planted shrimp tanks without harming shrimp, snails or fish. Needs mature biofilm and fine-leaved plants like Christmas moss and Susswasser for grazing. Rare in Singapore trade but occasional Carousell imports SGD 8-15 each. Soft, slightly acidic water, 24-28 °C suits them ideally.
Red-Claw Crab (Perisesarma bidens)
Brackish species requiring specific gravity 1.005-1.010. Pure freshwater kills them within weeks even though commonly sold for freshwater tanks. Growing to 5 cm, aggressive with fish and small tank mates. Setup should be 60 percent water, 40 percent land with mangrove roots or driftwood emerging. SGD 6-12 at C328 and Qian Hu. Mislabelling as “freshwater” is rampant — verify and adjust salt accordingly.
Pom-Pom Crab (Ptychognathus barbatus)
Fully aquatic species at 3 cm carapace with fur tufts on front legs used for filter feeding. Peaceful with fish and shrimp, tolerates pH 7.0-8.0 and moderate flow. Rare import at specialist LFS, SGD 10-20 when available. Works in planted community tanks with small tetras and rasboras. Soft sand substrate and low-flow zones help filter-feeding behaviour display.
Halloween Moon Crab (Gecarcinus quadratus)
Purple body, orange legs, land-biased with high humidity and a coconut-husk substrate. Reaches 5 cm carapace, lives 6-8 years. Occasionally at reptile crossover shops for SGD 20-40. Strictly terrestrial with a dip pool, not a tank species. Mentioned here because it is often mis-sold alongside vampires — check the setup requirements differ slightly (moon crabs need deeper substrate for burrowing).
Rainbow Land Crab (Cardisoma armatum)
Large West African terrestrial crab growing to 20 cm leg-span. Needs a 120 cm paludarium or large terrarium setup with deep moisture-retaining substrate. Aggressive with tank mates and each other. Occasional imports at specialist shops SGD 40-80. Check with NParks before purchase — some large crab species require permits as exotic invertebrates. A commitment species, not a casual pickup.
Fiddler Crab (Uca species)
Brackish species with the iconic oversized male claw. 3-4 cm carapace, active diurnal. Brackish setup at SG 1.005-1.010, ambient 24-28 °C, sand substrate for burrowing. Males wave the big claw to attract mates and display territory. SGD 5-10 at specialist Qian Hu or brackish-focused shops. Pair with mollies (brackish tolerant) or keep as species-only displays.
Panther Crab (Parathelphusa pantherina)
Indonesian stream crab with striking spotted carapace, growing to 5 cm. Semi-aquatic needing emerged rocks to climb onto. Aggressive and predatory — eats small fish and shrimp. Species-only setups preferred. Imports at Iwarna or Carousell specialists SGD 25-50. Spectacular species but not community-tank compatible despite how they are sometimes marketed. Pair with robust driftwood and hardscape from the decoration and substrate category.
Escape Prevention
Every crab except Thai micro and pom-pom escapes open tanks. They climb heater cables, filter intakes, silicone seams — anything with texture. Tight-fitting lids with no gaps over 5 mm are mandatory. Cover tall cords with smooth PVC sleeves. Lost crabs dehydrate and die within 24 hours in Singapore’s aircon-dried rooms. Every keeper loses one eventually — plan to minimise, not eliminate, the risk.
NParks Permit Check
Most common aquarium crabs are unregulated in Singapore, but larger exotic species (rainbow land crab, some coconut crab lookalikes) may fall under protected species controls. Verify the scientific name against NParks’ Agri-Food and Veterinary Authority import guidelines before buying rarer species. Commonly traded species at C328, Iwarna and Qian Hu have already cleared import compliance.
Related Reading
emilynakatani
Still Have Questions About Your Tank?
Drop by Gensou Aquascaping — most walk-in questions get answered in under 10 minutes by someone who has set up hundreds of tanks.
5 Everton Park #01-34B, Singapore 080005 · Open daily 11am – 8pm
