TankBud

Indo micro crab

Neorhynchoplax prima

Also known as Java giant micro crab, False spider crab, N. Rhynchophylla prima

FreshwaterCrab

Indo micro crab (Neorhynchoplax prima)

Care at a glance

Temperature
72–82°F
22–28°C
pH
6.5–7.8
Adult size
0.4 in
1 cm
Minimum tank
5 gal
20 L
Temperament
Peaceful
Social behavior
Social
Tankmates
With caution
Swim level
Bottom
Difficulty
Medium
Breeding
No record
Rarity
Very rare
Family
Hymenosomatidae
Origin
Bintan and Bangka islands, Indonesia

Overview

The Indo micro crab is a tiny, peaceful freshwater crab that is nearly invisible among moss and roots. It is best kept by someone with a little experience.

Did you know

One shop sells the Indo micro crab twice, under its own name and, at a higher price, as the Java giant micro crab. Both are Neorhynchoplax prima, a crab from Bintan, which lies a long way from Java.

Caring for the Indo micro crab

Keep Indo micro crabs as a group of half a dozen or more, so you actually see one now and then. Give the group at least 5 gal (20 L), with moss, fine leaf litter, roots and a gentle filter. They live in and on the plants, not on open sand.

Keep them in fresh water like the Thai micro crab, with stable, mature water above all. The temperature should run 72 to 82°F (22 to 28°C), with a pH of 6.5 to 7.8. The marine species register flags it marine by default, which the original description contradicts. Keep the flow gentle, and never treat the tank with copper.

Each crab sits in moss and root tangles, combing biofilm and tiny particles off surfaces. Feed powdered fry food, crushed flakes and a little frozen baby brine shrimp, and let the tank grow biofilm.

The Indo micro crab is peaceful, with no way to hurt a tank mate, and it is easy prey itself. Pair it only with dwarf shrimp, small snails and nano fish that leave shrimp fry alone.

There is no record of it breeding in captivity, and nothing is published on its larvae. Every crab in the trade is wild collected.

Good to know

Neorhynchoplax prima is a false spider crab in the family Hymenosomatidae. Ng and Chuang described it as one of eight new species in their 1996 revision of the family's Southeast Asian members. The holotype is a male 6.8 by 5.7 mm, so the whole crab is smaller than a fingernail. It is a flat disc of a body on long thin legs, and a giant only next to the Thai micro crab. Its name is simply Latin for first.

In the wild

The Indo micro crab was described from Pengudong on Bintan, the Indonesian island just south of Singapore. It is also known from Bangka Island off Sumatra. Ng and Chuang's 1996 description calls it a freshwater species, the first freshwater member of its genus found in Sundaland.

Common questions

What size tank does an Indo micro crab need?

An Indo micro crab needs at least 5 gal (20 L). It spends most of its time in the bottom.

What temperature and pH does an Indo micro crab need?

An Indo micro crab is comfortable at 72–82°F (22–28°C) with a pH of 6.5–7.8.

What does an Indo micro crab eat?

An Indo micro crab combs biofilm and tiny particles off moss and roots. Feed it powdered fry food, crushed flakes and a little frozen baby brine shrimp, and let biofilm grow in the tank.

How big does an Indo micro crab get?

An adult Indo micro crab reaches about 0.4 in (1 cm).

Related species