Orangeclaw Hermit Crab (Calcinus tibicen)

Orangeclaw Hermit Crab at a glance

The Orangeclaw Hermit Crab is Calcinus tibicen, a marine hermit crab in the family Diogenidae. Like every hermit crab, it carries an empty snail shell as its home and trades up to a bigger one as it grows. Each purchase supplies one live hermit crab. Before anything else, check that you can give it three things: a mature, fully marine aquarium, reef-safe fish for company and a steady supply of empty spare shells.

A hermit crab is often bought for the work it does, but its character is just as much of a draw. OATA, the UK ornamental aquatic trade body, counts hermit crabs among the crustaceans that perform a grazing function in the aquarium and will readily consume specific types of algae. It also says that marine crustaceans are very diverse and that most make excellent aquarium inhabitants. A crab picking its way over the rock, testing a new shell or turning over a scrap of food is one of the more absorbing sights in a marine tank.

Grazing is a help, not a complete algae solution. OATA points out that crustaceans sold to eat unwanted algae still need extra algae, offered as nori sheets, if they clear what is there, so plan to feed this crab rather than leaving it to live on what it finds.

About the name

"Orangeclaw" is the trade name, and it describes what most buyers notice first: the orange claws and legs, which in the gallery photograph are flecked with white. You may also see it listed as the orange claw hermit crab. Calcinus is a genus of hermit crabs, and the species name Calcinus tibicen, with Herbst named as its author in 1791, is the accepted name on the World Register of Marine Species.

What you receive and what to have ready

One purchase is one crab, so the quantity you enter is the number of hermit crabs that arrive. If you want more than one, remember that every extra crab needs its own share of food and spare shells.

Sex is guaranteed only when the selected option explicitly states male or female. This Calcinus tibicen listing has no sex-guaranteed option. The crab you receive may be male or female.

Each crab is an individual, and the shell it arrives in is borrowed, so its shape and colour can differ from the shell in the photograph.

The gallery photograph shows a hermit crab with white-speckled orange legs and claws, carrying a brown, coiled shell. Gallery images have been digitally enhanced to improve image quality. Natural colour, pattern, size and maturity can vary between live animals.

Have these ready before it arrives

• A fully marine aquarium that has finished maturing, with ammonia and nitrite both reading zero.
• Salinity, temperature and pH measured and within the guidance above.
• Live or artificial rock for grazing and for hiding after a moult.
• Several clean, empty shells in a range of sizes.
• Tank mates checked: reef-safe fish only, and a plan for any snails.
• Nori sheets and a small frozen food or pellet for extra feeds.

If you are planning a group of invertebrates, you can browse our marine invertebrate range; check each animal's own needs and its compatibility with the others before mixing them.

How a hermit crab lives

The World Register of Marine Species lists Calcinus tibicen as an accepted species in the family Diogenidae, within the decapods, the ten-legged crustaceans that also include shrimps and true crabs. The Wikipedia summary of the genus describes Calcinus as a genus of hermit crabs in that family.

As a crustacean, it has a hard outer skeleton, the exoskeleton, and a body divided into segments. OATA explains that a crustacean sheds its exoskeleton as it grows, that it is common to find empty "shells" from these moults in the aquarium, and that it takes a couple of days for the new exoskeleton to harden, during which the animal will often hide.

Two kinds of empty shell

New hermit crab keepers often panic at the sight of something empty in the tank. There are two very different things you may find:

• A cast exoskeleton. This looks like a complete, pale crab, legs and claws included, but it is hollow and light. It is a moult, a normal sign of growth, and the crab itself is usually tucked away in its shell nearby while its new skeleton hardens.
• An empty snail shell. This usually means the crab has swapped homes. Look for it in one of the other shells before assuming the worst.

Either way, the right response is to leave the rockwork undisturbed for a couple of days and check the crab quietly at feeding time.

Why the shell matters so much

A hermit crab's borrowed shell is its protection, and it has to find a bigger one as it grows. That is why OATA says hermit crabs should always be provided with ample food and plenty of spare shells: without them, they may attack snails for their shells. Spare shells are not an optional extra for this animal; they are part of its basic care, and the spare-shells section below covers them in detail.

Setting up the marine aquarium

Tank size

OATA's general rule is to buy as large an aquarium as you reasonably can. It recommends at least 40 litres for smaller species of crabs and shrimp and says larger crustaceans need a larger tank. Treat 40 litres as the absolute floor for a hermit crab, and remember that the fish you keep with it will also shape how big the aquarium needs to be.

Filtration

Whatever the size, OATA says a filter is essential. In a marine set-up that can be live rock with sufficient water flow, an internal or external filter, or a sump-based filter. A protein skimmer can also help, because it removes dissolved organic waste before that waste breaks down into more harmful substances. The RSPCA's aquarium environment guidance explains why the filter matters so much: animals release ammonia, which is toxic; beneficial bacteria in a working biological filter turn it into nitrite, which is also toxic, and then into nitrate, which is safer.

Rock and décor

OATA describes marine crustaceans as undemanding of décor, with one firm exception: live or artificial rock is essential, because it gives them places to graze and areas where freshly moulted individuals can hide. For a hermit crab, lay the rock out with that in mind:

• Build crevices and overhangs a crab can back into while its new exoskeleton hardens.
• Leave open sand between the rocks, where it can forage and where spare shells are easy to find.
• Keep rock stable, so that a climbing crab cannot bring a loose piece down.
• Set aside a spot on the sand for a small group of spare shells.

Maturity before stocking

A hermit crab should go into an aquarium whose filter is already running and whose ammonia and nitrite read zero. A new tank is the wrong place for it: the bacteria that process waste take time to build up, and crustaceans are sensitive to the ammonia and nitrite a young filter lets through.

Spare shells: the essential extra

OATA's advice on hermit crabs is specific: always provide ample food and plenty of spare shells, to prevent them attacking snails for their shells. A crab that has outgrown its shell, or cannot find a better one, will look for another, and a living snail can become the target.

How to provide shells

• Several at once. Offer a handful of empty shells rather than a single spare.
• A range of sizes. Include shells around the size of the one the crab wears and some a little larger, so there is always a next step up.
• Truly empty. Check each shell is clean and contains no living animal before it goes in.
• More crabs, more shells. Each extra hermit crab needs its own spares, or crabs end up competing for the same few.
• Top up over time. As the crab grows and moves up a size, add larger shells to keep the choice open.

Reading shell behaviour

A hermit crab that inspects spare shells, climbs in and out or swaps homes is doing something normal. A crab that is repeatedly harassing snails, or that seems crammed into a shell too small for it, is telling you the supply of shells or food has run short. Add more shells, check how much food is going in, and keep an eye on any snails in the tank.

Water quality for marine crustaceans

OATA describes marine crustaceans as usually undemanding of water chemistry. Its care sheet for marine crustaceans gives these suggested values as a general guide for the whole group, rather than figures measured for Calcinus tibicen alone:

OATA adds that if these invertebrates are kept in a reef aquarium, some values will need to be altered to accommodate more sensitive species. In practice, a reef tank is run to suit its most demanding residents, and the hermit crab fits in around them.

Salinity in practice

Salinity is the value to watch most closely in a marine tank. Measure it regularly and keep it inside the range above. Water evaporates but salt does not, so salinity creeps up between water changes: top up evaporation with fresh water, and use made-up salt water, mixed to the same salinity as the tank, for the water changes themselves.

Nitrate, calcium and magnesium

The nitrate figure is a ceiling, not a target. If a reading approaches 50 mg per litre, look at feeding and at your water change routine before it gets there. OATA includes calcium and magnesium in its guidance, so test them as part of a regular routine rather than guessing.

Stability

OATA warns that crustaceans can be stressed by even the smallest amounts of ammonia and nitrite, which may then cause them to develop various diseases. A heater and a separate thermometer keep the temperature within 24–26°C, and steady, routine testing does the rest.

Routine maintenance

A hermit crab shares its water with everything else in the tank, so the whole aquarium's routine is its routine. OATA's maintenance advice for marine crustaceans is straightforward.

Each week

1. Test ammonia, nitrite and nitrate so that you notice a rise before it becomes a problem.
2. Carry out a partial water change of 25% at least once every week, using a siphon to lift solid waste from the sand.
3. Replace it with made-up salt water at the tank's salinity.
4. Check the filter, and clean it as needed to prevent blockages.
5. If filter media needs cleaning, rinse it lightly in the tank water you have just taken out. Do not run it under the tap: any chlorine or chloramine present may kill the beneficial bacteria established in the media.
6. Clean the protein skimmer regularly, if you use one, so that it keeps performing.

A worked example

In a 100-litre marine tank, a 25% change is 25 litres each week. Mix those 25 litres of salt water in advance, check that the salinity matches the tank, siphon the same amount from the sand between the rocks, and refill. While the siphon is out, look along the rock for the crab and for any cast exoskeleton, and count the spare shells. A note of the date, the readings and anything unusual takes a minute and shows over time whether the routine is keeping up.

The routine at a glance

Around a moult

If you know the crab has just moulted, do the water change gently and avoid moving rock, because the crab will often hide for a couple of days while its new exoskeleton hardens.

Feeding the Orangeclaw Hermit Crab

OATA explains that marine crustaceans vary in their diets, but most species are omnivorous and will consume algae, detritus and small meaty items. It recommends a varied diet of nori algae sheets, small frozen items such as brine shrimp, or pellets. Hermit crabs are among the crustaceans OATA describes as grazers that will readily consume specific types of algae.

How often to feed

Many crustaceans graze throughout the day, and OATA says it is not possible to give a fixed number of feeds for them: it depends on how much natural food your aquarium holds. Use the tank itself as your guide.

• Plenty of grazing on the rock: small extra feeds, and check that they are eaten.
• Clean, bare rock: offer nori regularly, because a grazer that has cleared the algae still needs algae in its diet.
• Several crabs or snails sharing: feed a little more widely so that no crab goes short.

Avoid overfeeding

When you give extra feeds, take care not to overfeed. Uneaten food breaks down and releases toxic waste into the water, which is exactly what a crustacean copes with worst. Remove any food that is still lying untouched later in the day.

Food protects your snails

Feeding is part of keeping the peace. OATA links ample food with plenty of spare shells as the two things that stop hermit crabs attacking snails for their shells. Keeping both in good supply is the simplest protection for any snails in the tank.

Arrival and settling in

We hand-pack every order. The crab travels in a bag of pure oxygen inside an insulated poly box, with a heat pack if the weather needs one, and a licensed live-animal courier carries the parcel. We email the tracking number and your confirmed delivery date. Our delivery and Live Arrival Guarantee terms set out the details; on the day itself, work through these steps in order.

1. Make sure someone is at the address to take the parcel in. Live animals cannot be left unattended, and the guarantee depends on the parcel being received.
2. Start filming while the box is still sealed, with the outer box in view, and keep the unboxing video running in one continuous take. Every Live Arrival Guarantee claim needs this short video: parcel sealed, then opened, with the animal still inside its sealed bag.
3. Open the box and check the crab on the day it arrives, without stopping the recording.
4. Float the sealed bag in the aquarium for 20–30 minutes so that the crab acclimatises slowly.
5. Lift the crab into the tank and leave the bag water behind. Never pour bag water into your aquarium.
6. If something has gone wrong, contact us that day with your order number and the video. WhatsApp is quickest, and we will arrange a replacement or refund.

The first days

Before any new livestock goes in, check that ammonia and nitrite read zero. OATA advises increasing the number of animals slowly, because the bacteria in a matured filter need to increase each time livestock and feeding increase. Overstocking or stocking too quickly can cause new tank syndrome, when there are too few nitrifying bacteria to cope with the extra waste, and unhealthy levels of ammonia and nitrite may cause invertebrates to become ill or die.

• Have the spare shells in place before the crab arrives.
• If you need to move the crab, lift it by its shell with the crab inside, never by a leg or claw.
• Offer a small feed once it is out and exploring, and remove anything left over.
• Expect it to spend time learning the rockwork; watch for the warning signs below rather than for constant activity.

Health and moulting checks

OATA lists the changes worth watching for in marine crustaceans. Each animal varies a little, but a change from its normal pattern is what matters, and spotting it early lets you act before it becomes a real health issue.

Normal moult or a problem?

Hiding for a couple of days after a moult, with a complete cast exoskeleton lying nearby, is normal. A crab that struggles to leave its old exoskeleton, stays soft for longer than that, or stops moulting at its usual rhythm is showing one of OATA's warning signs, and the first step is to test the water.

Treatments in a mixed tank

Remedies meant for fish are not automatically safe for invertebrates. Before you treat anything in an aquarium that holds this crab, check that the product is suitable for crustaceans, and if in doubt ask us first.

When something looks wrong

Test ammonia, nitrite, nitrate, salinity and temperature first, because they are quick to check and easy to act on. Then look at shells and food: a crab short of either behaves differently. If the cause is still unclear, send us your readings and a short description of what you are seeing.

Tank mates and the snail question

OATA's compatibility advice for marine crustaceans has two sides. Crustaceans will generally mix with all fish considered reef-safe, while fish that are not reef-safe are likely to prey on them and should not be kept with them. Choose the fish first with that rule in mind, and check each species' own care information before it goes in.

Snails and other slow movers

The main risk from this crab runs the other way. OATA warns that hermit crabs should always have ample food and plenty of spare shells to prevent them attacking snails for their shells. It also notes that some scavengers, such as lobsters and crabs, are opportunistic and may prey on slow-moving aquarium inhabitants, so they should be mixed carefully.

• Suitable: fish considered reef-safe.
• With care: snails and other slow-moving animals, only with spare shells and food always available.
• With care: several hermit crabs together, each with its own supply of shells.
• Not suitable: fish that are not reef-safe, which are likely to prey on crustaceans.

What reef-safe means here

Reef-safe is a label for fish, and it is the one to check for every species in the tank. Confirm a fish's reef-safe status before you buy it rather than judging from how calm it looks in a shop tank, and apply the same check each time you add a fish later. One unsuitable addition can undo an otherwise settled community.

Different jobs in a clean-up crew

Crustaceans sold for the aquarium do different work, and it helps to know what each one is for. OATA describes hermit crabs as grazers of specific types of algae, peppermint shrimp (Lysmata wurdemanni) as eaters of unwanted Aiptasia anemones, and cleaner shrimp (Lysmata amboinensis) as shrimps that may eat parasites on larger fish. A hermit crab is the grazer of that group, and it will not do the other jobs.

Planning around the crab

Before adding the Orangeclaw Hermit Crab to an established tank, run through its companions one by one.

1. List every fish and confirm that each is considered reef-safe.
2. Count the snails. If there are any, add extra spare shells before the crab arrives and keep feeding steady.
3. Count any other hermit crabs, and add shells for each of them too.
4. Check the water against the guidance in the care tab, including salinity.
5. Add the new crab without other new livestock at the same time, so the filter only has one addition to absorb.

Keeping more than one hermit crab

If you keep several hermit crabs, plan the shell supply for the whole group: each crab needs spares of its own, and a shortage shows first as crabs contesting the same few shells or turning their attention to snails. Spread food across the tank at feeding time so that each crab can find some without competing, and add crabs gradually, in line with OATA's advice to raise livestock numbers slowly.

OATA's own last word on compatibility is to check before introducing any crustacean. If you are unsure about a particular fish or invertebrate, ask us before you order.

Questions keepers ask

How big does the Orangeclaw Hermit Crab get?

It grows in steps, shedding its hard exoskeleton each time it gets bigger, and it moves into a larger empty shell as it grows. Plan for that growth by keeping several spare shells in the tank, including some a little larger than the one it wears, rather than planning around a single fixed size.

What size aquarium does Calcinus tibicen need?

OATA recommends an aquarium of at least 40 litres for smaller species of crabs and shrimp and advises buying as large a tank as you reasonably can. The tank must be fully marine and mature, with a filter, live or artificial rock for grazing and hiding, and room for spare shells.

How many hermit crabs can I keep together?

Plan by resources rather than a head count. Every hermit crab needs its share of food and its own spare shells, so each crab you add means more empty shells in the tank, and OATA advises raising livestock numbers slowly so that the filter bacteria can keep up.

Is the Orangeclaw Hermit Crab a good choice for beginners?

It can be, once the marine aquarium itself is mature and stable. OATA describes marine crustaceans as usually undemanding of water chemistry, but ammonia and nitrite must read zero, the salinity must be right and spare shells must always be available.

What does Calcinus tibicen eat?

OATA notes that hermit crabs graze and will readily consume specific types of algae, and that most marine crustaceans are omnivores that eat algae, detritus and small meaty items. Offer a varied diet of nori algae sheets, small frozen foods such as brine shrimp, or pellets, and avoid overfeeding.

What temperature, pH and salinity does it need?

OATA's care sheet for marine crustaceans as a group gives 24–26°C, pH 7.9–8.3, salinity of 1.023–1.026 and carbonate hardness of 8–12 dKH, with ammonia and nitrite at zero and nitrate no higher than 50 mg per litre. In a reef aquarium, some values may need adjusting for more sensitive animals.

Is the Orangeclaw Hermit Crab aggressive?

The risk to watch is to snails. OATA advises that hermit crabs should always have ample food and plenty of spare shells to prevent them attacking snails for their shells, and notes that some scavenging crabs are opportunistic around slow-moving tank mates.

What can live with Calcinus tibicen?

Following OATA, marine crustaceans generally mix with fish considered reef-safe. Fish that are not reef-safe are likely to prey on them and should not share the tank. Keep snails only with plenty of spare shells and food, and check each species before mixing.

How does the Orangeclaw Hermit Crab arrive alive in the UK?

Each order is hand-packed, bagged in pure oxygen in an insulated poly box with a heat pack when the weather needs one, and carried by a licensed live-animal courier; we email tracking and your confirmed delivery date. Someone must be in to receive it. Keep a continuous unboxing video running from the sealed parcel, as every Live Arrival Guarantee claim needs one, then float the bag for 20–30 minutes.

Sources and further reading

• World Register of Marine Species: Calcinus tibicen for the accepted name, author and family.
• Wikipedia: Calcinus for the genus and its family.
• OATA: How to look after marine crustaceans for the group water values and advice on moulting, tanks, filtration, décor, feeding, maintenance, health checks and compatibility.
• RSPCA: fish environment for filtration and the nitrogen cycle.
• Tropical Fish Co delivery and Live Arrival Guarantee terms, linked in the arrival section, for packing, courier and claim requirements.