Thai micro crab (Limnopilos naiyanetri) care guide

Group
Other invertebrates
Other names
Micro spider crab, Thai spider crab, Hymenicoides naiyanetri
Family
Hymenosomatidae
Origin
Thailand: known only from the Tha Chin River (Nakhon Pathom province), on water hyacinth roots
Water
freshwater
Maximum size
2.5 cm
Temperature
21–27°C
pH
6.5–7.3
Hardness
4–10 dGH, 2–6 dKH
Minimum tank
20 litres
Care level
intermediate
Temperament
peaceful

Care

The Thai micro crab is one of the smallest crabs in the hobby: its flat, round carapace is at most about 1 cm wide, and with legs it spans about 2.5 cm. It is semi-translucent grey to light brown and covered in fine hairs that trap detritus, which may serve as food or camouflage. It is fully aquatic and has only been confirmed from one river in Thailand, where it lives on the floating roots of water hyacinth. It entered the hobby in 2008 and is still uncommon. Set-up: a small, mature, heavily planted tank of 20 litres or more with floating plants (dangling roots), moss and fine-leaved plants, and gentle flow from a sponge filter. Unlike many crabs it does not need to leave the water. It is shy and nocturnal, so plenty of cover is essential and you will see it more in a quiet species tank. Keep a group. Water: about 21–27 °C and pH 6.5–7.3. It is sensitive to water quality, so keep nitrate low and change water little and often. Role: it forages for detritus and biofilm among plants and moss, and probably takes tiny live prey. It is harmless to plants. Copper: copper-based medicines and some plant fertilisers are toxic to shrimp, snails and most invertebrates. Never dose copper in a tank holding this animal, and check fertiliser and medicine labels before use. Sources: Wikipedia (en.wikipedia.org/wiki/Limnopilosnaiyanetri). Checked October 2026.

Diet

Detritus, biofilm and fine organic particles picked from plants and moss; possibly tiny live animals. In the aquarium feed powdered foods, crushed flake, baby brine shrimp and fine frozen foods, letting some drift into the plants. A mature tank with plenty of mulm is important.

Breeding

No captive breeding has been recorded. Females release free-swimming larvae, which are assumed to develop in fresh water, but this has not been confirmed. Almost all animals sold are wild-caught.

Compatibility and tank mates

Peaceful and tiny. Keep with dwarf shrimp, small snails and very small, peaceful fish (microrasboras, pygmy Corydoras), or alone. Any fish large enough will eat it, and it is outcompeted for food by boisterous tankmates.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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