Vampire yellow crab (Geosesarma sp.)

A small crab that needs land, water and cover

The Vampire yellow crab is a small semi-terrestrial crab of the genus Geosesarma, sold here as one live crab per purchase at a 4 cm size grade. Before you order, plan where it will live. This is a crab for a humid, securely lidded paludarium with plenty of usable land and a pool of clean fresh water, not for an ordinary fish aquarium. Crabs in this genus spend most of their time on land and venture into the water when they choose, so the enclosure has to offer both.

Vampire crab is the name keepers and the Ornamental Aquatic Trade Association (OATA) use for crabs of the genus Geosesarma. The word yellow in this crab's trade name describes its colour form; it is not part of a scientific name. Geosesarma is an accepted genus in the family Sesarmidae, as recorded by the World Register of Marine Species. The exact species has not been identified, so the care advice here follows the genus Geosesarma and its care group.

Small size is part of the appeal and part of the challenge. At genus level, the Wikipedia summary of Geosesarma describes carapaces that are typically less than 10 mm across and notes that these crabs live and reproduce on land. A body that small explains why a tight lid and sealed cable gaps matter as much as the planting.

The land-based life cycle is worth understanding before you buy. Because the larval stages of these crabs take place inside the egg, they do not need open water to complete their development, and they spend their lives mostly out of it. A keeper who builds for a land animal first, and then adds a clean pool it can reach easily, is building for the way this crab actually lives.

You will find this crab in our aquarium shrimp and crustaceans collection, but its needs are different from those of fully aquatic shrimp. Think of it as a small animal that lives in a damp, planted garden with a pool, rather than as an aquarium invertebrate.

Before you order: a quick checklist

• An enclosure with a close-fitting lid and every cable or pipe gap sealed.
• A land area that covers most of the floor, built from moist soil and sand deep enough to dig in.
• A matured pool of clean fresh water with gentle exits.
• Moss, leaf litter, cork bark and plants for cover.
• A plan to feed small, varied portions and to remove leftovers.
• Copper-free products only, in and around the enclosure.

What you receive and what the photo shows

Each unit of quantity is one live crab, and the listing has a single 4 cm size grade that describes the size supplied. Treat that figure as a size grade rather than a carapace width or an adult-size promise. With the species unnamed, the genus-wide carapace figure above is general natural history, not a growth forecast for this particular form.

Sex is guaranteed only when the selected option explicitly states male or female. This Vampire yellow crab listing has no sex-guaranteed option.

The gallery photograph shows a crab with yellow-orange claws, purple eyes and darker legs standing on fine, mixed gravel beside a mossy rock. Gallery images have been digitally enhanced to improve image quality. Natural colour, pattern, size and maturity can vary between live animals. Your crab will have its own shading, and colour can look different under your lighting and against your substrate.

To keep more than one crab, increase the quantity when you order; each unit is another crab of the same size grade. Read the space and cover notes in the care sections first, because every extra crab needs its own burrows and hiding places.

Building a paludarium around life on land

Why the land area comes first

A keeper's care sheet written for Geosesarma sp. by The Tye-Dyed Iguana describes these crabs as spending most of their time on land while venturing into water. The Los Angeles Zoo, writing about one named relative, Geosesarma dennerle, describes a warm, humid, thickly planted habitat with wet soil beside fresh water, extensive use of land and burrowing. The zoo's account is about that species only, yet the shared picture is clear. Plan the enclosure as a damp land garden with a pool, not as an aquarium with a small island.

Getting the balance right has practical effects on welfare. A fully aquatic tank gives the crab nowhere to leave the water. An enclosure with too little land crowds every crab onto the same few surfaces and the same few hides. A generous land area with varied cover lets the crab choose between open and sheltered ground, and between land and water, which is exactly the choice a semi-terrestrial animal needs.

Choosing and securing the enclosure

Most glass enclosures built for paludaria or small terraria can work, provided the lid fits closely and every gap is sealed. Semi-terrestrial crabs leave the water readily, and a crab this small can slip through openings around cable holes, filter pipes, hinges and sliding panels. Check the lid before the crab arrives and again after every maintenance session, because a lid left slightly open after feeding is an easy way for a small crab to get out.

Choose a footprint that leaves room for a proper land area, a pool you can maintain and several separate hides. Floor area matters more than height for a crab that lives and digs on the ground, although a little height lets you plant the back of the enclosure and build cover at different levels.

Land area: substrate, burrows and cover

Use a deep, moisture-retentive substrate that will hold a burrow. The Tye-Dyed Iguana sheet builds the land from soil and sand, topped with moss, with leaf litter and cork bark for cover. Keep the substrate moist throughout so burrows keep their shape and the air above stays humid; the zoo's picture of wet soil beside fresh water is a good model.

• Soil and sand base: deep enough for the crab to dig a proper burrow, and firm enough that the tunnel does not collapse.
• Moss layer: holds moisture at the surface and gives the crab a soft area to forage over.
• Leaf litter: adds cover and places to search for food, and it can be topped up as older leaves break down.
• Cork bark and other hides: give more than one crab separate shelters and a secure place to retreat after moulting.
• Plants: dense planting, as in the zoo's description, adds shade, cover and humidity. Root plants firmly or grow them on wood and stone, because the crab digs.

Light for the planting

Moss and living plants need light to stay healthy, and healthy planting is what keeps the land area damp, shaded and full of cover. Give the enclosure a regular day and night, position any light so it does not bake one corner, and make sure there is always a shaded, humid retreat under cork bark or dense leaves.

Water area: easy to enter, easy to leave

Give the crab a pool of clean fresh water that it can walk into and climb out of without effort. Slope the substrate into the water, or build ramps from stones, roots or cork, so there is always a gentle exit on more than one side. Keep the pool large enough that its quality does not swing with every meal, and look after it like a small aquarium, which the next section covers.

Setting up the paludarium step by step

Building the paludarium in a sensible order saves a great deal of rework, and it gives the pool time to mature before the crab arrives. The sequence below suits most small crab enclosures; adapt it to the layout you have in mind.

1. Place the enclosure first. Choose a level, stable spot away from direct sun, radiators and draughts, close enough to a socket for any equipment you plan to run.
2. Mark out land and water. Decide where the pool will sit and keep most of the floor for land. A pool at the front or one end is easy to reach for water changes.
3. Build the transition. Create the slope, stones or roots that will lead from land into water, so the crab can always walk out. Check that no rock can shift or topple once the crab starts digging beneath it.
4. Add the substrate. Lay the soil and sand mix deeply across the land area and firm it lightly so burrows will hold.
5. Plant and add cover. Put in plants, cork bark and other hides, then top the land with moss and a layer of leaf litter.
6. Fill and mature the pool. Add clean fresh water, start any filtration you use, and let the pool mature. Test it until the readings are stable and safe.
7. Moisten and close. Dampen the land thoroughly, fit the lid, seal every gap and let humidity build for a few days before ordering.

A final check before the crab arrives takes only a moment: look for gaps around the lid, a clear exit from the water on more than one side, damp but not flooded substrate, and at least one hide for every crab you plan to keep.

Water quality, humidity and stable conditions

Look after the pool like a small aquarium

The pool may be small, but it is still water the crab lives beside and walks into. The RSPCA's guidance on aquarium environments explains why filtration matters: fish release ammonia, which is toxic, and a working biological filter lets beneficial bacteria convert it to nitrite, which is also toxic, and then to nitrate, which is safer. The same nitrogen cycle runs in a paludarium pool, where crab waste and leftover food break down, and in the damp substrate around it.

Mature the water section before the crab arrives, using the same approach you would use for a first aquarium. Our guide to preparing and maturing a first tank walks through that process. After that, keep the pool clean with small, regular partial water changes, prompt removal of leftovers and a close eye on anything decaying at the water's edge.

Test the water, then compare it with the right reference

OATA's care sheet for crayfish and freshwater crabs names vampire crabs among the animals it covers. It gives 22–27 °C, pH 7.0–8.0 and 8–18 °dH as general guidance for that whole group. Those figures describe a wide range of crabs and crayfish, so use them as a broad reference for the pool rather than an exact target for this unnamed form. From day to day, clean, stable, tested water matters more than chasing a single number.

If test kits are new to you, this explanation of which aquarium water values to test and why is a good place to start. You can then enter your own results in our water parameter matcher to see how your tap or pool water compares with published guidance.

Humidity and warmth

Humidity comes from the enclosure itself. Moist substrate, living moss and plants, open water and a close-fitting lid all help to hold it. The zoo describes warm, humid conditions for Geosesarma dennerle, and the keeper's sheet describes a humid, land-based set-up for Geosesarma sp., so aim for air that feels damp and a substrate that never dries out.

Measure rather than guess. A thermometer on the land side and another in the pool show whether a cool UK room is pulling the enclosure well below the group's general range. Place the paludarium away from direct sun, radiators and draughts, all of which cause fast swings in temperature and humidity.

Why stability matters

A small, humid enclosure changes quickly. Make every adjustment gradually, whether you are changing water, rearranging hides or adding plants. Top up evaporation with clean fresh water so the pool keeps its volume, and avoid big one-off water changes that alter the chemistry in a single step. A stable enclosure is easier on the crab and easier for you to read, because any change in its behaviour stands out.

Feeding an omnivorous scavenger

Vampire crabs are omnivorous scavengers, and variety is the heart of a good feeding plan. The Tye-Dyed Iguana's menu for Geosesarma sp. combines prepared crab food, small animal foods, fruit and greens. OATA's crab guidance also points keepers to a varied diet of animal and plant foods, and the Los Angeles Zoo describes Geosesarma dennerle scavenging on animal and plant material.

What to offer

• Prepared crab food: a convenient everyday food that is easy to portion and easy to spot if it is left uneaten.
• Small animal foods: small, protein-rich foods sized for a crab of this size, offered in modest amounts.
• Fruit: small pieces, removed before they soften or grow mould in the humid air.
• Greens: small pieces of leafy food, offered as part of the plant side of the diet.

How much, and where to put it

Offer small portions on the land area, on a flat stone or shallow dish near cover, so the crab can find the food and you can see what has been eaten. Start with a little and adjust to what disappears. It is far easier to add a second small portion than to clean up after an oversized one.

Remove leftovers, especially fruit and animal foods, before they spoil. In a warm, humid enclosure, uneaten food grows mould and fouls the substrate and the pool quickly, and prompt removal is the simplest way to keep a small paludarium healthy.

Variety rather than a single food

Rotate through the food types over the week rather than relying on one product. Variety makes it more likely that the crab receives what it needs, and it keeps feeding interesting for a scavenger that searches its surroundings for food. Watch appetite and activity over time; a crab that stops taking food it normally accepts is a reason to check water, humidity, temperature and hygiene.

Routine care, moulting and safe treatments

A simple maintenance rhythm

• Check the lid, the pool and the substrate surface whenever you feed.
• Remove uneaten food and any mould you see before it spreads.
• Change part of the pool water regularly with clean, tested fresh water.
• Re-moisten any substrate that is starting to dry, working with clean water.
• Top up leaf litter as older leaves break down, and trim plants that block the pool edges.
• Test the pool water at regular intervals and after any change to the set-up.

Moulting and hiding

Crabs grow by moulting. A freshly moulted crab is soft and vulnerable, which is one reason plentiful hides and secure burrows matter so much. A crab that spends time buried or tucked under cork bark is using its cover as intended, so resist the urge to dig it out. A cast-off shell can look surprisingly like a whole crab; look closely before assuming a loss.

Copper and other chemicals

OATA's crab guidance calls for treatments that are safe for invertebrates and free from copper. Read the ingredients of any medicine, water treatment or additive before it goes anywhere near the enclosure. Keep household sprays, polishes and insecticides away from the lid and any ventilation, because a small invertebrate in a closed, humid space has little protection from airborne chemicals.

When something seems wrong

Check the basics first: water test results, leftovers and mould, substrate moisture, humidity, temperature and any product used recently in or near the enclosure. Correct one thing at a time and make changes gradually, so the crab is not faced with a second sudden shift while it is already under strain.

Arrival day and settling in

Before the parcel arrives

Have the paludarium fully built before you order: land planted and moist, hides in place, lid sealed and the pool matured and tested. Make sure someone will be at the delivery address to receive the parcel, because live animals cannot be left unattended. Our delivery and Live Arrival Guarantee page sets out the terms in full.

Your crab is hand-packed by our team, travels in an insulated box with a heat pack when the weather calls for it, and is carried by a licensed live-animal courier.

Opening the parcel

1. Plan to open and inspect the parcel on the day it arrives.
2. Before you open anything, start a continuous unboxing video that shows the parcel still sealed, with the outer box visible.
3. Keep filming in one take as you open the box, so the crab can be seen inside its sealed packing before anything is disturbed.
4. Check the crab calmly, then move it onto damp land near cover in its ready paludarium, without adding any of the transport water, and let it walk off at its own pace.
5. Close the lid straight away, then leave the crab to settle while you watch quietly from a distance.

If anything has gone wrong, contact us the same day with your order number and the unboxing video. WhatsApp is the fastest route, and we will arrange a replacement or refund.

The first days

Expect the crab to explore, dig or disappear under cover for a while; that is normal behaviour in a new enclosure. Offer a small first meal once it has had time to settle, remove whatever is left, and resist moving hides to find it. Watch for the crab using both land and water over the following days, and keep up the same gentle routine of checking the lid, the pool and leftovers.

What the genus tells us

What can be said about this trade form's biology comes from its genus. According to the Wikipedia summary of the genus, Geosesarma are small freshwater or terrestrial crabs, typically less than 10 mm across the carapace. They live and reproduce on land, with the larval stages taking place inside the egg rather than in open water. The genus is recorded from India, Indonesia, Malaysia, Thailand, the Philippines, the Solomon Islands and Hawaii.

That list describes the whole genus, not the home of this crab. Because the Vampire yellow trade form has no species name, no single country or habitat can honestly be attached to it. What the genus picture does give you is a clear model for the enclosure: damp land, cover, fresh water close at hand and a life lived mainly out of the water.

We leave home breeding out of this guide. Reproduction details, clutch sizes and development times differ between species, and without a species name the responsible approach is to concentrate on good everyday care: damp land, clean water, varied food and plenty of cover.

Fish, other crabs and shared enclosures

Fish

OATA advises caution when crabs share an aquarium with fish, and for this crab the simplest answer is a dedicated set-up. A paludarium built mainly as land, with a pool the crab can walk out of, is not a fish habitat, and a community fish tank gives a semi-terrestrial crab nowhere to live as it needs. Give the Vampire yellow crab an enclosure of its own.

More than one crab

If you would like several crabs, plan for them together from the start. Every crab needs access to land, water, food and cover without having to pass through another crab's hiding place, so increase burrowing depth, hides and feeding spots with each addition. There is no fixed number that suits every enclosure; start modestly, watch how the crabs share space and food, and add animals only when the layout clearly has room.

Other crabs, crayfish and invertebrates

The dedicated-set-up approach applies to other crustaceans too. The simplest plan is to keep this paludarium for Geosesarma crabs rather than mixing in crayfish or unrelated crabs, whose size, habits and water needs differ. If you enjoy aquatic invertebrates as well, keep them in their own aquarium.

Plants and décor

Choose plants that enjoy damp, humid conditions, and use moss, leaf litter and cork bark freely. Because the crab burrows, anchor plants firmly, grow some on wood or stone, and expect the substrate surface to change as tunnels appear. Keep décor free of sharp edges at the pool margins and away from the lid seal.

Who this crab suits

This crab rewards keepers who enjoy building a small planted world and watching what happens in it. It suits someone who is happy to maintain a humid enclosure with both land and water, keep the pool clean, feed small varied portions and check the lid every time.

• A good fit: paludarium and terrarium keepers, planted-tank hobbyists ready to build a land area, and anyone who likes observing small animals that dig and forage.
• A poor fit: someone hoping to add a crab to an existing community fish aquarium, or a keeper who wants an animal to handle.

Treat the crab as an animal to watch rather than hold. When you do need to move it, guide it gently into a small container rather than picking it up, and keep the lid closed whenever your hands are out of the enclosure.

Vampire yellow crab questions answered

Is the Vampire yellow crab a water crab or a land crab?

It is a semi-terrestrial crab. Crabs of this genus spend most of their time on land and venture into water, so it needs a humid paludarium with a large land area and a pool of clean fresh water rather than a fully aquatic tank.

How do I give a Vampire yellow crab both land and clean fresh water?

Build most of the enclosure as damp land, then add a pool of clean, tested fresh water with sloping substrate, stones or roots so the crab can walk in and out easily. Mature the pool before the crab arrives, remove waste promptly and refresh part of the water regularly.

What substrate and hiding places suit Geosesarma sp. crabs?

Use a deep, moisture-holding mix of soil and sand that keeps its shape when the crab digs, then add moss, a layer of leaf litter and cork bark or similar shelters. Plenty of cover lets the crab burrow, hide and moult in security.

What should I feed a Vampire yellow crab?

Offer a varied omnivorous menu: prepared crab food, small animal foods, and small pieces of fruit and greens. Feed small amounts on the land area and remove leftovers before they spoil, because uneaten food fouls a warm, humid enclosure quickly.

Are copper-based treatments safe for this crab?

No. Treat the Vampire yellow crab as a copper-sensitive invertebrate: use only invertebrate-safe, copper-free products in or near its enclosure, and read the ingredients of any medicine or water treatment before use.

Can Vampire yellow crabs live with fish?

A dedicated set-up is the better plan. OATA advises caution when crabs and fish share an aquarium, and a paludarium built mainly as land leaves little space for fish anyway, so give the crab a lidded enclosure of its own.

Which species is the Vampire yellow crab?

The species has not been identified. It belongs to the accepted genus Geosesarma in the family Sesarmidae, and Vampire yellow is a trade name for this colour form, so its care follows the genus and its care group.

How do I keep a Vampire yellow crab enclosure humid?

Humidity comes from the set-up itself: keep the soil and sand substrate moist, grow moss and plants, include the freshwater pool and fit a close lid. Re-moisten dry patches with clean water and keep the enclosure away from radiators, direct sun and draughts.

Can I handle the crab?

It is an animal to watch rather than hold. If you need to move it, guide it gently into a small container instead of picking it up, and keep the lid closed whenever your hands are out of the enclosure.

How does the crab arrive, and what should I do first?

It is hand-packed by our team and carried by a licensed live-animal courier, and someone needs to be at the delivery address to receive it. Start a continuous unboxing video with the parcel still sealed, keep filming as you open it, then move the crab gently onto damp land near cover in its ready paludarium without adding the transport water. Our delivery page explains the Live Arrival Guarantee terms.

Does a Vampire yellow crab need a lid?

Yes. Use a close-fitting, escape-resistant lid and seal the gaps around cables and pipework. Small semi-terrestrial crabs leave the water readily and can slip through narrow openings, and the lid also helps keep the air humid.

Why is my crab often out of sight?

Geosesarma crabs dig and use cover, so time spent in a burrow, under leaf litter or behind cork bark is normal. Check that the lid is secure and that food is being taken, keep conditions stable and avoid digging the crab out.

Sources and further reading

• World Register of Marine Species: Geosesarma – accepted genus and its place in the family Sesarmidae.
• Wikipedia: Geosesarma – genus natural history, including small carapace size, a life cycle on land and the recorded range of the genus.
• OATA: How to look after crayfish and freshwater crabs – UK trade care guidance for the group, including vampire crabs: clean water, copper-free treatments, a varied diet, caution with fish and general water figures.
• The Tye-Dyed Iguana: Vampire crab care sheet – a keeper's care sheet for Geosesarma sp. describing a humid, land-based set-up with soil and sand, moss, leaf litter, cork cover and a varied menu.
• Los Angeles Zoo: Vampire crab – a zoo account of Geosesarma dennerle: humid, planted habitat beside fresh water, burrowing and a mixed diet.
• RSPCA: Fish environment – why filtration and the nitrogen cycle matter in an aquarium, which applies equally to a paludarium pool.