Thai Micro Crab (Limnopilos naiyanetri)

The Thai Micro Crab is one of the smallest and most fascinating freshwater crabs available in the aquarium hobby. Renowned for its tiny size, delicate appearance, and distinctive hairy claws, this peaceful species is a favourite among shrimp keepers and nano aquarium enthusiasts.

Growing to little more than the size of a fingernail, Thai Micro Crabs spend much of their time perched amongst mosses, plants, and driftwood, using their feathery claws to collect tiny food particles from the water. Their gentle nature and unique feeding behaviour make them an incredibly rewarding species to observe, especially in well-planted aquariums.

Native to the Tha Chin River in Thailand, these fully aquatic crabs inhabit slow-moving freshwater with dense aquatic vegetation. Unlike Vampire Crabs, Thai Micro Crabs spend their entire lives underwater and do not require a land area.

🌿 Why Choose Thai Micro Crabs?

🦀 One of the smallest freshwater crabs in the world
🌿 Fully aquatic – no land area required
🦐 Ideal for shrimp and nano aquariums
🧤 Unique hairy claws used for filter feeding
💚 Peaceful and fascinating to observe
🌱 Thrives in densely planted aquascapes
✨ Excellent addition to natural freshwater aquariums
🏆 A rare and unusual freshwater invertebrate

📏 Care Requirements

🧬 Scientific Name: Limnopilos naiyanetri
📛 Common Name: Thai Micro Crab
🏠 Tank Size: 20L+ recommended
📏 Adult Size: Approximately 1–1.5cm across the carapace (up to 2.5cm including legs)
🌡️ Temperature: 22–28°C
⚗️ pH Range: 6.5–7.8
💧 Water Hardness: Soft to moderately hard water (4–15 dGH)
🧘 Temperament: Extremely peaceful
🍽️ Diet: Biofilm, micro-organisms, powdered invertebrate foods, crushed pellets, spirulina powder, baby brine shrimp, and fine frozen foods
👥 Group Size: Best kept in groups of 5 or more

🏡 Aquarium Setup

Thai Micro Crabs thrive in mature, heavily planted aquariums with plenty of surfaces for grazing and hiding.

A suitable aquarium should include:

🌿 Dense mosses such as Java Moss or Phoenix Moss
🪵 Branching driftwood
🪨 Small rocks and crevices
🍂 Leaf litter
🌱 Fine-leaved aquatic plants
💧 Gentle filtration with minimal water flow

These tiny crabs spend much of their time climbing through plants and mosses, collecting microscopic food particles with their specialised claws.

A mature aquarium rich in natural biofilm is highly recommended, as newly established tanks often lack sufficient natural food sources.

🐠 Compatibility

Thai Micro Crabs are extremely peaceful and should only be housed with similarly gentle species.

Suitable tank mates include:

✅ Neocaridina Shrimp
✅ Amano Shrimp
✅ Small snails
✅ Chili Rasboras
✅ Ember Tetras
✅ Celestial Pearl Danios
✅ Otocinclus

Avoid keeping them with:

❌ Bettas
❌ Gouramis
❌ Cichlids
❌ Crayfish
❌ Larger crabs
❌ Large shrimp species that may outcompete them for food
❌ Any predatory fish

Because of their tiny size, even many peaceful community fish may view them as food.

🍽️ Feeding & Behaviour

Thai Micro Crabs are omnivorous scavengers and filter feeders, spending much of the day collecting microscopic food particles from plants and décor.

Their diet should include:

🟢 Spirulina powder
🦠 Biofilm
🦐 Baby brine shrimp
🩸 Finely crushed frozen bloodworm (occasionally)
🟤 Powdered shrimp and crab foods
🌱 Crushed algae wafers

As they feed slowly, it is important to ensure food reaches them before faster fish or shrimp consume it.

They are most active during the evening but are frequently seen exploring throughout the day in heavily planted aquariums.

⚠️ Important Notes

Thai Micro Crabs are best suited to well-established aquariums with abundant natural biofilm and stable water conditions.

Due to their exceptionally small size, they are masters of camouflage and may disappear into mosses and plants for long periods. This is completely normal behaviour.

These crabs are delicate and should never be exposed to copper-based medications, which are highly toxic to crustaceans.

During moulting, Thai Micro Crabs become particularly vulnerable and require plenty of hiding places. Do not remove their discarded shells, as they often consume them to recycle valuable minerals such as calcium.

Although breeding has occasionally been achieved in captivity, it remains relatively uncommon, making these crabs a rare and highly desirable addition to freshwater aquariums.