Orange Back Vampire Crab (Geosesarma sp.)

Choose the Orange Back Vampire Crab for a humid paludarium

The Orange Back Vampire Crab is a small, mainly land-living crab of the genus Geosesarma, sold as Geosesarma sp. because this colour form has not been matched to a named species. Its carapace carries a vivid orange saddle across the back, while the front edge of the shell, the legs and the claws are a deep purple-black. The claw tips fade to ivory, and the bright yellow eyes have a dark central bar. Those eyes explain the trade name: Wikipedia notes that “vampire crab” refers to the yellow eyes of some species, not to anything the crab eats.

Vampire crabs are land crabs that need fresh water close by. Fishkeeper describes them spending most of their time out of the water, and Practical Fishkeeping notes that they are independent of the sea, so they never need salt or brackish water. That combination makes the Orange Back Vampire Crab a classic animal for a planted paludarium: a lidded enclosure that is mostly land, with a small, clean pool.

They are crepuscular, meaning most active at dusk and dawn, so you will see the most of them in the evening as the lights dim. In a well-planted set-up they climb roots and moss, pick over leaf litter and sit at the water’s edge with their claws raised, and the orange back shows up strongly against dark wood and green moss.

Check the fit before you order

The Orange Back Vampire Crab sits with our other shrimps and crustaceans. You can also browse the full freshwater crabs and crayfish category or go straight to the Geosesarma vampire crab range to compare colours.

Know what one purchase supplies

One purchase quantity supplies one live Orange Back Vampire Crab. The only option is “Standard”: this form is not graded into sizes, so crabs are sent at the size available on the day, usually young adults or adults. The photographs show the colour form, not the individual crab you will receive. The amount of orange on the back varies from crab to crab, and the purple of the legs can look almost black in some lights.

Sex is not specified. If you are building a breeding group, ask us before you order and we will tell you what is available at the time. Read our delivery and live arrival terms before ordering, and have the enclosure running, warm and tested before the crabs arrive.

Plan the group before you buy

• One crab: fine as a single display animal, or as an addition to an existing group of the same form.
• A small group: Fishkeeper advises one male with several females unless the enclosure is very large, because males may fight.
• Room for each crab: our vampire crab buying guide points out that a litre count alone does not measure crab habitat; plan separate hides and routes so each crab can feed, shelter and reach the water without meeting the others all the time.

Understand the name and the species behind it

Geosesarma belongs to the family Sesarmidae. It is a large genus: Wikipedia lists 59 species, and a 2019 paper by Shy and Ng in ZooKeys counted 64 recorded species, most of them from Indonesia. The genus ranges from India through Thailand, Malaysia, Indonesia and the Philippines to the Solomon Islands and Hawaii.

Aquarium vampire crabs were long sold without scientific names. In 2015 Ng, Schubart and Lukhaup formally described two of them from central Java, Geosesarma dennerle and Geosesarma hagen, noting that both had been in the aquarium trade for many years under the popular name “vampire crabs”. Other trade forms remain unidentified; Practical Fishkeeping’s profile of a traded vampire crab describes one believed to be an undescribed species. Colour names such as “Orange Back” describe what the crab looks like, not which species it is, and different sellers use different names for similar-looking crabs.

Wikipedia also records that both Javan species are threatened by illegal over-collection for the aquarium trade. Looking after your crabs well, breeding them where you can and never releasing them all help reduce pressure on wild populations.

Tell males from females

Watch the crab from below when it climbs the glass. Fishkeeper explains that females have a wider, oval abdomen flap, while males have a narrow, tapering one, and that males usually have larger claws. Avoid catching crabs just to check: handling stresses them, and a crab that has just moulted is soft and easily injured.

Expect a small crab with a long reach

Size figures differ because sources measure different things. Wikipedia describes Geosesarma as typically less than 10 mm across the carapace, and the 2015 description measured a male Geosesarma hagen at 13.1 × 11.7 mm. Practical Fishkeeping gives 2–3 cm and Fishkeeper gives up to 3 cm, figures that take in more than the shell alone. In practice the Orange Back Vampire Crab is a small animal whose legs make it look larger than its shell, which is why a modest enclosure can suit a small group if it offers enough land, cover and climbing surfaces.

Plan the enclosure around floor space

Because these crabs live on surfaces rather than in open water, usable land area matters more than total volume. Use our tank volume calculator for the pool section, so you know how much water you are conditioning and changing each week, and plan the land around hides, climbing routes and feeding spots.

Build a paludarium with more land than water

Fishkeeper recommends a paludarium or vivarium-style tank with about two-thirds land and one-third water, and a tight-fitting lid. Vampire crabs are skilled climbers and escape artists, so block every hole where cables, pipes or tubing enter the enclosure. Our vampire crab guide adds that the land is the main habitat, and that the water should have several easy exits.

Fishkeeper suggests a sandy land area with roots, marginal or terrestrial plants and rocky caves for hiding, particularly after moulting. Java moss on the land and in the water gives shelter and helps the crabs climb out. The water area should be heated and filtered like a normal aquarium and deep enough for a crab to submerge fully when it moults, with shallow, stable footholds at the edges.

Lay out the enclosure in zones

Live plants rooted in the land area help hold humidity and give the crabs more to climb. Keep the enclosure away from direct sunlight and radiators, which can overheat a small, closed set-up quickly.

Match temperature, humidity and water values

Practical Fishkeeping gives 22–28°C and high humidity for vampire crabs. Fishkeeper also gives 22–28°C, with hard, alkaline water at pH 7.5–8.5 and 10–25 dH. OATA’s UK care sheet for freshwater crabs as a group gives 22–27°C, pH 7.0–8.0, 8–18 dGH and 10–15 dKH. The sources differ at the edges, so we suggest the range they share: 22–27°C, pH 7.5–8.0 and 10–18 dGH.

None of these sources gives a humidity figure. Keep the air damp with a lid, moist substrate and moss, and measure at the level where the crabs live: our vampire crab guide warns that condensation on the glass is not a full measure of humidity or temperature. Tap water in the UK ranges from soft to very hard depending on where you live, so test your own water before you set up, and use our water matcher to compare it with these values. Always treat tap water with a conditioner to remove chlorine or chloramine, and do not add salt: these are freshwater crabs.

Use these values as a checklist

Our water chemistry guide explains what pH, general hardness and carbonate hardness mean and how to test them.

Feed a varied diet with plenty of animal food

Practical Fishkeeping describes vampire crabs as omnivores whose diet is largely meaty. Its profile lists dry food, freeze-dried animals, earthworms, springtails and live house crickets, and notes that they also eat moss and graze algae. Fishkeeper suggests bloodworm, Mysis and finely chopped krill or prawn, plus vegetable matter, and says they accept pellets, algae wafers and specialist crab foods. OATA advises feeding freshwater crabs once a day, leaving the food for about 30 minutes and then removing what is left, with sinking crustacean pellets, algae wafers and vegetables such as courgette and cucumber among the options.

Live foods suit the crab’s hunting habits. A springtail culture added to the land area also helps clean up leftovers, and the smallest small house crickets make an occasional chase-and-catch meal. For the staple, algae wafers and freeze-dried bloodworm are easy to portion.

Build one measured crab meal

• Feed at dusk: the crabs are most active as the light fades.
• Feed on land: put food on a flat stone near the water’s edge, where every crab can reach it.
• Keep it small: a piece each crab can finish in about 30 minutes, as OATA suggests.
• Rotate: pellet or wafer one day, frozen or freeze-dried meaty food the next, live insects now and then, and a little vegetable.
• Clear up: lift out leftovers before they spoil; damp, warm enclosures turn uneaten food mouldy quickly.

Acclimatise new crabs calmly

OATA recommends the floating-bag method for crabs and crayfish. It suits the Orange Back Vampire Crab well, with one change: release the crab onto the land at the water’s edge rather than dropping it into the pool.

1. Switch off the enclosure light and keep the room dim.
2. Float the sealed bag in the pool for 10 minutes so the temperatures even out.
3. Open the bag and add small amounts of enclosure water to it over at least 30 minutes.
4. Tip the crab gently onto the land beside the water, adding as little bag water as possible.
5. Pour the bag water away down a household sink, never outdoors.

Use a first-week checklist

New crabs often hide for several days. That is normal behaviour for a shy, crepuscular animal, not a sign of illness.

Keep the enclosure clean without disturbing the crabs

OATA recommends changing 25% of the water at least once a week, testing ammonia, nitrite, nitrate, pH and hardness weekly, and treating replacement water with a tap water conditioner. Rinse filter media in water removed from the enclosure, never under the tap, so the useful bacteria survive. Fishkeeper also stresses regular partial water changes in the water section to keep nitrate low.

Follow a weekly routine

1. Test the pool water before changing any of it.
2. Siphon out about a quarter of the pool water, cleaning only the open bottom.
3. Refill slowly with conditioned water at the same temperature.
4. Remove food scraps, mould and any obviously rotting leaves from the land.
5. Check the lid, seals and cable gaps for anything a crab could squeeze through.

Support healthy moulting

Crabs grow by shedding their shell. OATA notes that moulting is frequent and that a discarded skin can look just like a dead animal, which is normal. Fishkeeper explains why caves matter after a moult and why the pool must be deep enough for a crab to submerge: a freshly moulted crab is soft and vulnerable until its new shell hardens.

Help a crab through a moult

• Count crabs, not shells, before you assume a loss.
• Leave a hiding crab alone; do not lift its cover to check on it.
• Keep the water in OATA’s medium-hard range, which supplies the minerals a new shell needs.
• Watch for incomplete shedding, which OATA lists among the signs of ill health.

Watch the crabs and act on changes

Learn what normal looks like in the first month: crabs hidden by day, out at dusk, feeding on land and dipping into the pool. OATA lists the changes that point to a problem.

Pair each observation with an action

If you are worried, test the water first and contact us with your readings, the enclosure size and what you have seen.

Breed vampire crabs without a larval stage

Many crabs hatch as tiny swimming larvae, but most Geosesarma do not. Shy and Ng found that over 90% of Geosesarma species with known egg sizes have large eggs and direct development, and they observed females of the Taiwanese species they described brooding young crabs under the abdomen flap. Wikipedia likewise notes that the larvae develop inside the egg. Fishkeeper reports vampire crabs breeding in home aquariums: the female carries eggs under her abdomen for several weeks and miniature crabs hatch directly. Practical Fishkeeping says females of the form it describes carry eggs about every six months, with about 50 to 60 young hatching.

Raise the young crabs

• Keep the water shallow at the edges: Fishkeeper notes that young crabs stay mostly in or near the water and become more land-living as they grow.
• Give cover: dense moss and leaf litter give the young places to hide and feed.
• Feed fine food: crushed pellets and a springtail culture reach small crabs that cannot compete at the adults’ feeding stone.
• Do not expect a self-running colony: our vampire crab guide notes that breeding does not mean a group will sustain itself; numbers depend on food, cover and space.

Choose companions with care

OATA warns that freshwater crabs can hunt small, slow fish and recommends a dedicated set-up. Fishkeeper calls vampire crabs non-community animals best kept in a species-only enclosure, although some keepers succeed with small, fast, peaceful fish. Our vampire crab guide adds that small fish and shrimp may become prey and that other crab species have different needs. Use the tank mates checker to screen any fish you are considering for the pool.

Screen every companion

Compare the other vampire crab colours

Several vampire crab forms look alike at first glance. The Orange Vampire Crab carries its orange on the claws, while the Orange Back keeps its claws purple and wears the orange on the shell. The Red Devil Vampire Crab is the named species Geosesarma hagen, the Purple Vampire Crab is Geosesarma dennerle, and the Golden Eye Vampire Crab is another unidentified trade form. Keep each form in its own enclosure.

Never release crabs, plants or enclosure water

OATA reminds keepers never to release aquarium animals or plants into the wild. Dispose of old substrate, leaf litter and water through household waste or the drain, never into ponds, streams or gardens.

Answer Orange Back Vampire Crab buying questions

Is the Orange Back Vampire Crab its own species?

Not as far as anyone has published. It is a trade name for an orange-backed colour form of Geosesarma whose exact species has not been identified, so we list it as Geosesarma sp. Two vampire crabs known from the aquarium trade, G. dennerle and G. hagen, were formally described in 2015; many other trade forms are still unidentified.

How big does an Orange Back Vampire Crab get?

Small. Wikipedia gives Geosesarma shells as usually under 10 mm across, while Practical Fishkeeping gives 2–3 cm and Fishkeeper up to 3 cm, figures that take in more of the body and legs.

Does it live in water or on land?

Mostly on land. It needs a humid enclosure with far more land than water, plus a shallow, clean freshwater pool deep enough to submerge in when it moults. Fishkeeper suggests about two-thirds land and one-third water.

What temperature does it need?

Keep it within 22–27°C. Practical Fishkeeping and Fishkeeper both give 22–28°C and OATA gives 22–27°C for freshwater crabs, so 22–27°C satisfies all three.

What does it eat?

It is an omnivore that takes a lot of animal food: crab or crustacean pellets, algae wafers, frozen bloodworm or Mysis, springtails and small crickets, plus some vegetable matter. Feed in the evening on the land area and remove what is left.

Can I keep it with fish or shrimp?

A crab-only enclosure is safest. OATA warns that freshwater crabs hunt small, slow fish, and small shrimp can be eaten. Some keepers manage small, fast, peaceful fish in the pool, but slow bottom-dwellers should be avoided.

How many should I keep together?

Fishkeeper advises one male with several females unless the enclosure is very large, because males may fight. Sex is not specified on this listing, so ask us before ordering if you are building a group.

Will vampire crabs breed in my paludarium?

They can. Geosesarma females carry large eggs under the abdomen and the young hatch as tiny crabs with no larval stage, so no salt water is needed. Plenty of cover and fine food help the young survive.

Can vampire crabs escape?

Yes, they climb well and squeeze through gaps. Use a tight-fitting lid and seal every hole where cables or pipes enter the enclosure.

Consult the care references

• OATA: How to look after crayfish and freshwater crabs — UK trade body care sheet: water values, weekly maintenance, feeding, acclimatisation, moulting, health signs and compatibility.
• Wikipedia: Geosesarma — family, size range, distribution, number of species, development inside the egg and the origin of the name “vampire crab”.
• Ng, Schubart and Lukhaup (2015), Raffles Bulletin of Zoology 63: 3–13 — formal description of Geosesarma dennerle and Geosesarma hagen, two vampire crabs long sold in the aquarium trade.
• Shy and Ng (2019), ZooKeys 858: 1–10 — Geosesarma species count, egg size and direct development across the genus, and females brooding young crabs.
• Practical Fishkeeping: Vampire crab, Geosesarma sp. — size, temperature, humidity, diet, activity pattern and breeding frequency of a traded vampire crab.
• Fishkeeper: Vampire Crab (Geosesarma spp.) — land-to-water layout, water chemistry, sexing, group make-up and breeding notes.
• Tropical Fish Co vampire crab buying guide and delivery terms — our own set-up, feeding and live arrival guidance.