Scarlet Vampire Crab (Geosesarma sp.)

Choose the Scarlet Vampire Crab, an all-red Geosesarma for a planted paludarium

The Scarlet Vampire Crab is a small land crab of the genus Geosesarma coloured red from end to end: our photographs show a scarlet shell, scarlet claws and red legs, set off by large, bright yellow eyes. It is one of the colour forms sold as "vampire crabs", a group of tiny, mostly terrestrial crabs from Southeast Asia that suit a humid, planted paludarium. At dusk it comes out of its cave to patrol the moss, pick over leaf litter and visit the water's edge, and a small group of red crabs moving through green moss is one of the most striking sights in fishkeeping.

This listing is for one live Scarlet Vampire Crab sold as Geosesarma sp. The genus is certain; the species behind the trade name "Scarlet" has not been identified, and we do not invent one. Like every vampire crab, it lives mainly on land and needs a paludarium with moist ground, cover, a shallow freshwater pool and a lid that closes every gap.

Learn what the scientists found

Vampire crabs were in the trade for years before they had names. In 2015, Peter Ng, Christoph Schubart and Christian Lukhaup published a peer-reviewed description of the two commonest trade forms as new species, Geosesarma dennerle and Geosesarma hagen, and established that both are native to central Java, settling years of conflicting dealer claims about Sulawesi, Krakatau and the Riau Islands. Practical Fishkeeping reported that the names honour the two aquatic companies that supported the fieldwork. The paper also confirmed that Geosesarma is a large genus of terrestrial crabs from Southeast Asia, then numbering 53 species, which is why so many trade colours remain unidentified. The genus belongs to the family Sesarmidae (WoRMS).

Separate it from our other red vampire crabs

We sell several red vampire crabs, and they are not interchangeable. The only one with a confirmed species is the Red Devil Vampire Crab, Geosesarma hagen. Its scientific description records a dark brown front to the shell and legs, an orange or yellow rear, bright orange to reddish-orange claws and bright yellow eyes, with the amount of orange varying so much that some crabs are almost completely orange. The Scarlet form is sold as a distinct crab, red all over.

A shared colour is not evidence of a shared species, and mixing forms makes behaviour and any breeding unpredictable. Our guide to choosing a vampire crab explains why we keep identified groups apart, and you can compare every form in our Geosesarma vampire crab category.

Know what arrives with each Scarlet Vampire Crab

• One live Scarlet Vampire Crab per purchase, in the standard size we currently import.
• The sex is not selected or guaranteed.
• Shades of red vary from crab to crab, so the photographs show the form rather than the individual.
• Delivery days and Live Arrival Guarantee terms are on our delivery page. Build and run the enclosure before ordering.

Check the sex of each crab

Look at the underside. OATA describes how crabs are sexed by the shape of the flap tucked under the body: narrow and pointed in males, wide and rounded in females. The Fishkeeper profile adds that males usually carry larger claws and can be territorial, so it suggests one male with several females unless the enclosure is very roomy. If you buy several crabs, sex them in the first week and move extra males to another set-up.

Size the enclosure for a crab that lives on the floor

Vampire crabs are tiny. Adult shells of the two Javan species in the 2015 description measured roughly 1.1–1.5 cm across, while hobby sources give 2–3 cm body length (Practical Fishkeeping) and a maximum of 3 cm (Fishkeeper). As the Scarlet form is unidentified, plan for a crab in that range. What they need is floor and cover rather than depth of water: OATA recommends at least 60 litres for a small group of crabs, as long and wide as possible, with only a half to a third of the tank holding water.

Run a three-step space check

1. Base area: 60 litres or more (OATA) on a long, wide footprint; our litre calculator works it out from your measurements.
2. Land share: about two-thirds land and one-third water, as the Fishkeeper profile recommends.
3. One hide per crab: plus spares, so a moulting crab can always retreat.

Build the paludarium in the right order

Wild vampire crabs in central Java live on the slopes of small valleys and on the banks of streams and rivulets, hiding under and between rocks in dense vegetation, and sometimes digging burrows in loose ground at the water's edge. The 2015 paper found adults seldom in the water and mostly on moist banks, with juveniles often in or right beside the water. The Fishkeeper profile describes the same picture: rocky caves and burrows near a stream, shallow warm water, and roots and plants for climbing.

Follow this build sequence

1. Land base: slope rocks, pebbles and gravel to form a bank, then cap it with sand or soil (OATA), so that it drains and stays damp rather than waterlogged.
2. Pool: leave a third of the floor as a shallow pool, deep enough for a crab to submerge fully when moulting (Fishkeeper), with gentle exits on every side.
3. Hardscape: fix rocky caves, cork bark and roots firmly so nothing can collapse on a crab.
4. Plants: add marginal or terrestrial plants on the land, and grow Java moss in and out of the water as cover and a bridge between land and pool (Fishkeeper).
5. Leaf litter: scatter dried leaves over the land for cover and grazing.
6. Equipment: fit a heater and a small filter in the pool, cover the intake with sponge and seal all cable exits.
7. Run it in: mature the filter (see how to cycle the filter) and check that the land stays humid and warm before any crab goes in.

Light it and place it well

OATA recommends overhead lighting to keep a proper day-night cycle, and advises placing the tank away from draughts, heat sources, direct sunlight, loud noises and vibration. That matters for a humid paludarium: sunlight can overheat a closed enclosure, and a draughty spot makes it hard to hold temperature and humidity on the land.

Seal the lid: vampire crabs escape

A Scarlet Vampire Crab will climb out of any gap it can reach. OATA says crabs are very good at escaping and need a secure lid with every hole blocked, and the Fishkeeper profile calls vampire crabs great escape artists. The lid that keeps them in also keeps the humidity up, so it does two jobs.

• Choose a lid that closes flush on all four sides.
• Fill cable cut-outs with foam and cover any ventilation gap with fine mesh.
• Keep cables, tubing and plant stems away from the rim.
• Put the lid back the moment you finish feeding or misting.
• Do a head count at dusk, when the crabs are out.

Hold humidity, temperature and water quality steady

Practical Fishkeeping describes vampire crabs as kept in high humidity, and the Fishkeeper profile says they bask in humid air. Neither gives a percentage, so judge by the land: the surface and the moss should stay moist, with fresh rather than stagnant air. A hygrometer and a thermometer on the land tell you far more than condensation on the glass. Remember that the pool heater warms the water first; check that the land is warm enough too.

The Fishkeeper profile calls vampire crab water hard and alkaline, which matches the tap water in much of the UK, but supplies vary from soft to very hard, so test before you build. Dechlorinate all water, including misting water. Our water matcher checks your readings against the crab's needs, and the page on pH and hardness explained covers the basics.

Keep a simple weekly routine

Test the pool once a week for ammonia, nitrite, nitrate, pH and hardness, and change at least 25% of its water, as OATA recommends for crabs. Rinse the filter sponge in old tank water, never under the tap. On the land, lift out uneaten food and mouldy leaves, top up leaf litter and check the humidity and lid seals before closing up.

Feed like a hunter, in small portions

Wild vampire crabs are mainly hunters of small ground insects. The 2015 description found G. hagen apparently carnivorous, feeding at least partly on insects living on the ground, and G. dennerle eating mainly small insects such as grasshoppers, probably with midge larvae and plant detritus. Practical Fishkeeping adds that captive vampire crabs take dry food, freeze-dried food, earthworms and springtails, hunt live house crickets and graze moss and algae at night. The Fishkeeper profile lists bloodworm, mysis shrimp, finely chopped krill or prawn, vegetable matter, pellets, algae wafers and crab foods.

Plan a measured week of meals

Feed once a day at dusk, when the crabs become active (Practical Fishkeeping describes them as crepuscular and nocturnal). OATA's rule is to leave food for about 30 minutes and then remove what is left. A tropical springtail culture seeded into the land gives the crabs live prey and eats leftover food and mould.

Settle new crabs in quietly

Make sure ammonia and nitrite read zero and that the land is warm and humid before the crabs arrive. Follow OATA's floating-bag method: lights off, float the closed bag in the pool for 10 minutes, then add small amounts of tank water over at least 30 minutes. Let the crab walk out at the pool edge beside moss or a cave, with as little bag water as possible. Our page on how to acclimatise new arrivals covers the method.

Check four things in the first week

Keep Scarlet Vampire Crabs on their own

The Fishkeeper profile rates vampire crabs as non-community and recommends a species-only tank. They will hunt small fish, so slow bottom-dwellers should be avoided, although some keepers have kept them with small, fast, peaceful fish. OATA advises a dedicated set-up for crabs in general. In practice, the best companions for a group of Scarlet Vampire Crabs are the springtails in their soil.

Run any other idea through our compatibility checker first. Browse the full range of freshwater crabs and crayfish and our shrimp and crustacean range for other invertebrates, each in its own set-up.

Look after moulting crabs and watch for trouble

Crabs grow by moulting. The Fishkeeper profile notes that vampire crabs need water deep enough to submerge fully while they moult and rocky caves to shelter in afterwards. OATA warns that a shed shell can be mistaken for a dead crab, so check before you remove anything, and that crabs are very sensitive to copper: use only treatments labelled safe for invertebrates.

Match each sign to a response

Raise baby crabs with no larval stage

Vampire crabs are among the crabs that have been bred in home enclosures. The Fishkeeper profile explains why: the female carries the eggs under her abdomen for several weeks, then miniature crabs hatch directly, with no swimming larval stage. Practical Fishkeeping reports that females carry eggs about every six months and that 50–60 young hatch from each clutch. In the wild, young vampire crabs stay in or very close to the water and become more terrestrial as they grow, so give them a shallow, mossy edge and plenty of tiny food. Young crabs are small and vulnerable to adults, so moving a carrying female or the young to a separate tank improves survival. Keep breeding groups to a single form, so you know what you are raising. OATA notes that smaller crabs often live only a couple of years, which makes a breeding group the best way to enjoy Scarlet Vampire Crabs for longer.

Answer Scarlet Vampire Crab buying questions

What is a Scarlet Vampire Crab?

It is an all-red colour form of vampire crab, genus Geosesarma (family Sesarmidae), sold under the trade name Scarlet Vampire Crab. Our photographs show a scarlet shell, claws and legs with bright yellow eyes. The species behind this trade name is not identified, so we list it as Geosesarma sp.

Is the Scarlet Vampire Crab the same as the Red Devil Vampire Crab?

It is sold as a different form. The Red Devil is Geosesarma hagen, which its scientific description records as dark brown on the front of the shell and legs, orange or yellow behind, with bright orange claws, although some are almost completely orange. The Scarlet form is red all over. Keep the two in separate enclosures.

Is it the same as the Red Tomato Vampire Crab?

They are sold as separate trade forms. Neither has been identified to species, so a similar red colour cannot prove they are the same animal. If you keep both, give each its own enclosure.

Does it live in water or on land?

Mostly on land. Wild vampire crabs in central Java live on moist banks under rocks and in dense vegetation, and adults are seldom found in the water. Give it about two-thirds land and one-third water, as the Fishkeeper profile recommends, with water deep enough to submerge in when it moults.

What size enclosure does it need?

OATA recommends at least 60 litres for a small group of crabs, in a tank that is as long and wide as possible. The crabs are small, but they need floor space, climbing cover and a hiding place each.

What temperature and water does it need?

Aim for 22–27°C, which fits OATA (22–27°C) and the vampire crab profiles in Practical Fishkeeping and Fishkeeper (22–28°C). Use dechlorinated fresh water at pH 7.5–8.0 and 10–18 dGH, inside both the Fishkeeper and OATA ranges, and keep the air humid.

What do Scarlet Vampire Crabs eat?

They are omnivores that love animal food. Wild vampire crabs eat mainly small ground insects; in captivity offer crab pellets, frozen bloodworm and mysis, springtails and other small live foods, with some vegetables, moss and algae. Feed once a day at dusk and remove leftovers after about 30 minutes.

Can I keep it with fish?

It is best kept without fish. The Fishkeeper profile rates vampire crabs as non-community and says they will hunt small fish; slow bottom-dwellers are most at risk. Shrimp are also likely prey.

Will Scarlet Vampire Crabs breed?

They can. Vampire crabs have no larval stage: the female carries her eggs for several weeks and miniature crabs hatch directly (Fishkeeper). Practical Fishkeeping reports about 50–60 young per clutch, roughly every six months.

Consult the care references

• Ng, Schubart & Lukhaup (2015), Raffles Bulletin of Zoology 63: 3–13 — peer-reviewed description of two vampire crabs from central Java: habitat, behaviour, diet, colours and adult sizes.
• Practical Fishkeeping: Vampire crabs named after aquatic companies — news report on the 2015 naming of Geosesarma dennerle and G. hagen.
• Practical Fishkeeping: Vampire crab, Geosesarma sp. — vampire crab feature by Chris Lukhaup: size, temperature, humidity, diet and brood size.
• Fishkeeper: Vampire Crab (Geosesarma spp.) — species profile of vampire crabs: origin, size, water values, land-to-water ratio, diet, behaviour, sexing and direct development.
• WoRMS: Geosesarma De Man, 1892 — the genus Geosesarma De Man, 1892 and its family, Sesarmidae.
• OATA: How to care for crayfish and freshwater crabs — UK trade guidance for crabs: water values, aquarium size, land area, secure lid, acclimatisation, feeding, maintenance, sexing, moulting and health checks.
• Tropical Fish Co delivery policy — current dispatch days and Live Arrival Guarantee terms.