About the species

The micro spider crab is a small, fully aquatic freshwater crab from Thailand with a carapace of only about one centimetre and long, hairy legs. Unlike almost every other crab in the trade it needs no land area — it lives its entire life underwater. Hairy claws are used to filter fine particles from the water.

Facts

• Latin name: Limnopilos naiyanetri
• Common name: Micro Spider Crab - Aquatic
• Size: Carapace about 1 cm, leg span 2–2.5 cm
• Lifespan: 1–1.5 years

Behavior

The micro spider crab lives entirely underwater and needs no land area — which sets it apart from almost every other crab in the trade. It is peaceful, sociable and practically defenceless, so keep it in a group with small, calm species. It is shy and most active at dusk, preferring to sit in floating plant roots and moss.

Reproduction

• Females often carry yellow to orange eggs under the broad abdominal flap
• The larvae need no brackish water, but captive rearing is not yet established
• Sexing is simple: males have a V-shaped abdominal flap, females a U-shaped one

Feeding

The micro spider crab filters and grazes fine particles and feeds on:

• Microorganisms caught with the setae on its claws
• Biofilm on moss, roots and filter sponge
• Detritus and algae

Supplement with finely divided food:

• Powdered food for fry
• Artemia nauplii
• Spirulina tablets and leaves that grow biofilm

Aquarium

• Minimum aquarium size: 20 litres
• Substrate: Moss and floating plant roots matter more than the choice of substrate

Difficulty level

🟡 Moderate

Recommendation

Keep it in a group in a well-established aquarium with floating plant roots, moss, gentle flow and a sponge filter. It is shy and most active at dusk, so expect it to be invisible much of the time. Choose its company carefully: the crab is practically defenceless and the risk is that it gets eaten, not that it harms anything.