Hermit Crab Care Guide

Land Hermit Crab Care Guide

With Species Specific Info

Please do not use this elsewhere without permission.

Download a text only version:

Despite their name hermit crabs are very social and need to be kept with species partners. In the wild they usually live in huge colonies and lone captive crabs will often become depressed,which in turn can impact greatly on their health. There is a common perception that they are easy to keep and almost “throw away” pets, much like goldfish, but hermit crabs have very specific care requirements and lifespans which can reach into multiple decades. Unfortunately the incorrect care that arises from these perceptions and the PPS (post purchase stress) they are so prone to means many do not survive to their first captive moult. It is important to make sure that your crabitat is set up ready before purchase, you have a good diet available and you give them the time needed to destress and acclimatise to captivity.

Choosing your crabs

Finding a Seller

When picking your hermits do your best to source from a seller that has been giving them the proper care while with them, if the conditions at the store/previous owner's home are wrong then the hermits kept there may have a lessened chance of survival even when moved to correct conditions. Lack of humidity, a cold tank, no food or water, no spare shells and discarded legs or claws are all signs something is wrong and it is likely the crabs will be sick or extremely stressed. Ask how long they have had the crabs, what food they get and if they treat the water they receive. The answers to simple questions can help you get an idea of how well the crabs are being looked after. Adopting can be a rewarding experience and, if you are certain you know what you are doing, will give a second chance to crabs that may have already successfully had their first moult in captivity.

It can be tempting to “pity purchase” crabs from poor conditions in shops, but however noble this thought is you will be encouraging them to bring more in. Try politely approaching the shop and bringing up any issues, or offering to provide some printed or emailed care information if they are interested. Always stay polite and non-confrontational, rudeness or anger won't get the point across any better and won't help the animals.

You may be unable to find any within travelling distance and decide to buy online. Where possible buy in person so you can check the crabs over, but if you choose to buy from a seller online make sure the transport method will be next day delivery guaranteed, and check their packaging policy. If you are unsure or can't find one on their site don't be afraid to send a polite query asking them how they will be packed. They need to be well packed with packaging outside their tub/s as well as plenty inside (moss is often used). Make sure you know what day they will arrive and allow them to warm up slowly if cold. If it is going to be very hot or cold then wait until better weather to buy, better to be patient than to lose them to winters freezing temperatures!

Make sure you take suitable transport for bringing them home with you in case the seller provides some that is not really suitable. A bottle of dechlorinated water, a plastic tank with a comfy lining of clean moss, a few bits of food and a towel to cover them and minimise stress are a good basic purchase kit.

What To Look For

Where possible know what size and species you are getting before buying, so you can get a collection of shells together that will fit now and in the next size up, and so you can perfect the crabitat conditions for their species. Hermit crab shops can be good, you need to keep looking and in the cases of poor care politely educate.
Avoid painted shells or shells decorated with glued on objects, hermit crabs are forced out of their shells and into painted ones in poorer countries to be sold on to the pet trade, a process that is extremely traumatic for a hermit crab and can cause them to drop limbs, become ill or die. The paints and glues also pose risks as hermits will test just about anything, including their own shells, as a potential food source, and even paints marked as non toxic are not safe. There is also the risk of a shell that has not completely dried becoming stuck to the hermit crabs soft abdomen, meaning they are unable to get free to moult or change shells. This leads to stress, difficulty moving around and often even with intervention death.

Once you have found a suitable source to pick from ask to have a closer look at the crabs. If any are burrowed right down leave them be to destress or moult in peace and have a look at the ones on the surface. Are there any that pulled back into their shells when you approached, can you see one climbing or walking around, is one perched over the food dish eating? Hermit crabs are generally nocturnal so you may not see any out, but if you do these would be good ones to start with. Gently picking them up (don't tug if they hold onto things though) and placing them on a flattened palm slowly will help stop them becoming too frightened, they may pinch if they are but keeping your hand as flat as possible and not tugging at them will let them settle down and release you without them being hurt. If you can hold them carefully without their BP (big pincher) reaching skin then do so, bigger ones in particular can be painful which is another reason they are unsuited to children. Move slowly and talk quietly to minimise fear reactions, and let them come out of their shell in their own time.

Looking at the legs and claws, see if any are missing or deformed in some way, and if the toes are pointed or worn down. Missing legs can be a sign of stress or injury which may have happened in the wild or since capture. Missing or part missing legs and claws will grow back with moults, so don't immediately dismiss the crab unless you are determined to avoid any with even potential stress caused issues. Worn down toes generally mean they have not shed for a while and will easily renew when they do. Deformities can be caused by problems with moults and are more of a warning sign.

On the body, look for any signs of wounds, infected looking patches or mites. Shy crabs and crabs that are feeling insecure will be harder to examine but never try to pull or force them out further. Infections and mites require treatment, infections potentially have spread to other crabs and mites find it easy to so alert the keeper to what you have found immediately. Crab mites will be tiny bugs running over the body of the crab itself, tiny white mites just on the food in the tank are food mites and far less of an issue, they often occur in hermit crab tanks due to the high humidity and temperatures.
- Its worth mentioning that if mites appear in your colony a deep clean and Hypoaspis miles predatory mites can be used to treat them.

Drooped antenna and general lethargy are often signs something is amiss, if the tank conditions are correct it is probably something wrong with the crab itself.

Limpness can be a sign of moulting and surface moulting is something that needs to be acted upon to protect the hermit crab from the others in the tank and potential cannibalism, but if accompanied by a foul smell of rotting then unfortunately the little one has passed away.

If a crab is active, waggling his/her antenna and generally looking healthy then it has the best chance of making it through to the first moult and beyond. Always pick at least three hermies to allow for their social nature, but if possible (they need plenty of room) go for at least four so that if one passes they still have a group. Overcrowding can be a big issue but they do best in a group.

When you get them home

Carefully unpack each hermie one at a time, with a brief check that they have not been injured on the way, then give them a quick and gentle dechlorinated water bath and put them in their already prepared new home. Offer them a few different foods, making sure there is animal protein alongside some fresh and dried fruit and veg, calcium sources like cuttlefish bone and a high energy treat like organic pure honey. As tempting as it is to handle them and keep checking on them your hermies will need time to adjust and destress, so cover the tank at night and other than the basic daily maintenance leave them be as much as possible. Often they will start changing shells and burrowing down almost right away, starting a moult on arrival is common if they have not had the needed conditions for a while.

New hermies will also often burrow down to destress. Moulting and destressing can take days, weeks or even occasionally months so patience is needed. Never dig them up unless it is an absolute emergency, and avoid moving or placing heavy objects in the tank as you may collapse their little chamber.
Some new hermit crabs will pass away within the first few months, having never moulted, and if conditions are all correct it is considered a PPS death. All you can do is look after them to the very best of your abilities and if you do smell the death smell give them a respectful burial.

Shells

Having a variety of spare shells available for your colony is vital, they change them as they grow and for comfort, and a lack of shells to change into can lead to the sometimes fatal shell fights. Aim for at least three of the right size per hermit crab (more is better) and have the next size up and down available as well in case they wish to change. Shells suited for large and jumbo sized hermies can be difficult and expensive to source so ensuring you have them before yours reach that size is a must.

Shells with holes, rough insides or other damage should be discarded as hermies store water inside their shells and rough or jagged textures can harm the soft abdomen they hide inside. If a hermit crab shop does not have what you need, email and ask if they can get it in for you.

Different species like different types of shells, the commonest and easiest to keep purple pinchers (Coenobita clypeatus) tend to favour turbo shells and others with round openings, which come in a wide range of colours and safe polished or carved styles. Turbos are one of the easiest shells to find and are often available in craft stores, bags of shells sold for home decoration and on eBay. Some species like the viola (Coenobita violascens) tend to prefer different openings like murex or horse conch, although my largest has taken a polished turbo as his.

Favoured Shells By Species:
Purple Pinchers (Coenobita clypeatus): Turbos and other similar species.
Viola (Coenobita violascens): Murex, horse conch and other similar species.
Ruggies (Coenobita rugosus): Turbos and similar.
Indo (Coenobita brevimanus): Turbos and similar.
Ecuadorian (Coenobita compressus): D shaped openings like Thais species and babylonia.
Strawberries (Coenobita perlatus): Turbos and similar.
Blueberries (Coenobita purpureus): Turbos, will also wear D shape openings.
Cavis (Coenobita cavipes): Turbos, turbans and similar.
Aussie (Coenobita Variabilis): Turbos, babylonia and similar.

They won't always stick to this, as with my large viola if a shell takes their fancy (or better suited are unavailable) they will take other types. Experimentation is key, shells that look too big, small or are of a different type to the ones normally favoured could prove a huge hit and if they remain unclaimed for lengthy periods swaps with other keepers may be possible.

New shells can be cleaned by boiling in dechlorinated water (fresh or with marine salt added) to remove any nasties particularly if second-hand. Unusable shells can be used for decoration, sold on, used in DIY tank projects, added to water bowls to provide climbing points or crushed into a grit for the crabs to get calcium from.
Say NO to painted shells. Painted and decorated shells are often forced onto hermit crabs and pose great risk to their health, nature has provided many varied and beautiful natural shells and many are available safely carved or polished.

Shell fights, even with many options offered, can still occur, and can result in injury or death for the victim. Sometimes another crab will decide it just has to have that particular shell, and they will attempt to force the other out. A shelless crab is very vulnerable so isolating them gently if they do not find a replacement and offering them alternatives will prevent them being harmed in the meantime, humidity must be kept high to prevent them suffocating.

Housing

Setting your crabitat up correctly is vital to giving your hermit crabs the best possible life.

The tank

Plastic storage tubs can be adapted to suit a hermit crabs needs, and for a temporary emergency measure a critter keeper with the ventilation covered can be used, but ideally your colony needs a large glass tank to live in. The minimum size needed depends on the size of your colony and the crabs itself. For instance, if you only have three crabs but one is a jumbo you will need a significantly bigger tank than a colony of five teenys. You also need to factor in the future growth of your group, both the potential size of the ones you have and allowing for extra if you will wish to expand the colony in the future. A bare minimum of 20 US gallons should be given to a max of four mediums, but if you can give them more then do and always remember as they grow they WILL need more space. In the wild they roam for huge distances and they need plenty of space to moult safely. Crabitat size is definitely a case of bigger is better, but you must make sure you can maintain the correct conditions for the crabs as well.

The lid needs to be very secure as hermit crabs are notorious escape artists and will push up the lid or find holes that will allow them to escape.
Having an isolation tank set up on standby in case of emergency or rescues that need quarantine is a good idea, it needs a good substrate depth, dishes and hides, as well as a heat source that can be switched on when needed.

Substrate

A mix of play sand (sold all year around from argos), and organic coir (reptile stuff is fine but can be sourced cheaper from reputable suppliers like fertile fibre) is perfect. The sand should be in a sealed bag when bought, and damp when opened with no obvious mould, black sand or bits of detritus. If the sand is contaminated take it back for a refund, playsand should be cleaned and contaminate free so something was wrong with the batch. You can also sieve the sand for peace of mind if you wish.

The ratio varies from keeper to keeper, some say 5:1, others say 1:1. My personal preference is roughly 4:1 but if you start with the sand then add in the coir until you are happy with the consistency you should be fine. The addition of coir helps to break down waste instead of it simply rotting as in pure sand, and it provides better conditions for tunnelling. Never use coloured sand, and calci sand must be avoided as it can set into a solid clump around burrowed hermit crabs, meaning they are unable to surface. Plain playsand is a much better alternative to the more expensive reptile ones. At least 2 – 3x the height of the largest crab should be provided.
It needs to be damp and sand castle consistency, so that it clumps together when squeezed. Water-logging can lead to bad bacteria and stagnant water forming in the bottom of the tank, which can cause health issues and foul odours.

Spot cleaning can be done as needed, simply picking bits of poop and food out as needed, and full cleans should be occasional events done when all crabs are on the surface. Tank custodian isopods (woodlice) can be added which help keep the tank clean and serve as an occasional snack and source of enrichment for the hermits.

Post shed viola with some healed scrapes.

Young C. violascens are a vibrant red until they grow older.

C. violascens partially drawn into its polished turbo shell.

New crabs will need time to destress and often have poor quality shells that they will change in time.

Hermies often enjoy snacking on moss as well as sleeping in it.

Decoration

Cork bark, mopani wood, coconut hides, safe untreated woods like oak and dried cactus wood (choya/cholla) can all be used as decorations and will be nibbled at by the hermit crabs, providing them with tannins and other nutrition. Boiling in hermit crab safe salt water or soaking in the salt water then baking will clean the wood and help inhibit or treat mould growth, some keepers suggest 2x strength mix for particularly stubborn issues.
Coconut hides can be made cheaply with coconuts from the supermarket (roughly 80p or less each). Check the coconut by shaking to hear the milk sloshing inside and sniff it. Coconuts should smell of coir, if they smell like coconut scent products they have gone off and should not be used for food. Once you have drained the liquid out by piercing an eye scour a line around the centre then break the shell, removing the flesh to use as you wish (eat yourself or dry/freeze for the hermies), and breaking or cutting a hole for the door. I break bits off with a pair of pliers (be careful if you do this and take precautions), others use power tools to cut or break the door in. The fibres on the outside of the coconut will gradually be nipped off by the crabs so it gives them something else to do and another addition to their diet.

Plastic or silk plants that are free from paint, exposed wires, glitter and fragrance can be used to provide hiding and climbing places, draped from second levels they will create an attractive ladder and provide a splash of colour in the tank. Exposed wires can be siliconed over with aquarium safe brands as long as you leave it to cure fully before use. The crabs will pick at it and damage it over time, particularly silk plants, so keep an eye on them and when they become ratty or if you see one eating parts remove them.

Natural moss like organic sphagnum or the exo terra forest moss that comes in blocks are another favourite with hermit crabs, they will pick at and sleep in it and the moss also helps keep the humidity levels up. If using the dried moss boiling in dechlorinated saltwater and rinsing repeatedly is advised as a lot of much comes out that would soil the tank. Sphagnum moss is usually sold live so a rinse with fresh dechlorinated is better.

Hemp and jute nets can be made from organic twine if boiled once made(this bit will stink), and hung as a hammock or down a wall to add more climbing areas, or to provide a ladder to second levels. I made mine with crochet but they can also be knitted or hand knotted. Hermit crabs love climbing and they will walk upside down on the underside as well as exploring the top. Keepers use these to provide second levels or place lots of shells in to create a shell shop, which helps stop the shells becoming dirty and buried.
Shower caddies and soap dishes held up with suction cups can also be used to add in extra levels, with fake plants or branches used to provide stable ladders to and fro.

Other items like barnacles, shells, pebbles and resin hides can be used to give the hermies more places to explore and provide hides for security during the day. Everything needs to be clean and anything that is painted or varnished should be left out so they do not pick at and ingest anything toxic. Metal should be kept out of the tank.
Scallop shells make good natural supplement dishes, and resin reptile ones are a more natural looking approach, but tupperware containers and well cleaned plastic tubs are fine.

Heat and Humidity

All hermit crabs need a high level of humidity to live, they breathe through gills and if the humidity drops to low they begin to suffocate which can lead to streaking without a shell and death. If the tank has too much ventilation it can be covered on the outside with clingfilm or other methods but ideally a more permanent solution should be found. 70% should be the bare minimum, the more it drops below this level the higher level of gill damage that may be caused.

Moss can be added and kept damp to boost humidity, and gentle tank spraying will also assist with care being taken not to over saturate the substrate. Its best to use a digital hygrometer to monitor the conditions since humidity is so vital to their survival. Bubble pools are a fancier option to boost humidity greatly and give the hermits a new experience, but are best used in fresh since the salinity of the salt water can become too high.
Heat can be provided with heat lamps or heat mats attached to the side of the tank above substrate level. Care needs to be taken, particularly when using lights, to make sure that the crabs are not able to reach the source or get burnt, and that hot glass is not sprayed with water. If using plastic housing extra care needs to be taken to prevent warping or other issues from the heat. Emergency foil blankets and polystyrene sheets on the outside of the tank can help to keep the crabitat warm during colder months.

Species specific conditions can be found on their care sheets.

Crocheted hemp nets held up by suction cups are an option for giving your crabs more space to explore.

Diet

Commercial diets targeted at hermit crabs are not a complete diet. Some are ok as treats, but they don't provide the variety and well rounded nutrition needed, and often contain additives that are harmful. Good hermit crab foods involve a varied diet of fresh and dried foods, which is much more natural and healthy, and gives you the chance to add in colour boosting foods to enhance your crabs carapace colour after sheds.
These are the main hermit crab food groups and examples of each:

Protein
Protein is absolutely vital, hermies without enough can resort to cannibalism sometimes. Fresh and dried foods can be offered from various different groups.
Sea foods like krill, bloodworm, shrimp, fish, squid, shellfish and crab are all good options as long as you make sure it hasn't had any salt or anything added, or been treated in some way.
Insects like mealworms, crickets, locusts etc, are usually offered dried but hermies will often go after live isopods and eat dead ones.
Meat, unseasoned stuff like chicken, beef etc, bones can be cracked to let them get at the marrow.
Plant proteins like lentils, broccoli, corn, millet, flax seeds etc.
Fresh stuff is usually removed after one night/day since in the tank conditions it spoils fast.
A lot of keepers will buy dried items as "store cupboard" foods to rotate alongside fresh foods which can be frozen if needed to store. Fish counters will often let you buy one or two shrimp which helps since they eat so little. Protein in some form should be offered every day.

Calcium
Calcium is needed for the carapace and general health, keep a bit of cuttlefish bone available all the time so they can access it as needed. Crab carapace, crushed eggshell, barnacle shells, dried starfish (ensure these have not been treated with things, craft store ones are unsuitable) and crushed oyster shell are all good, offer a few types
regularly so they get variety.

Seaweed
In the wild any crabs with ocean access will eat this and its very nutritious. Spirulina is expensive but well worth it, cheaper options you can get include kelp, bladderwrack and dried seaweed sheets. The seaweed sheets get demolished in my tank overnight.

Fruit and Vegetables
Like most food groups these can be offered fresh or dried, BUT with dried you have to ensure it has not had any sulphates, sugar or other stuff added so buying organic is best. Keeping dried on hand to rotate and adding in fresh regularly is a good way to go, some crabs can be a bit picky but will often eat on the second or third attempt so persevere. Coconut is almost always a universal favourite, you can buy a whole one, make the shell into hides and freeze or dry the meat.
Fruits like mango, apple, pear, strawberry, blueberries, coconut, banana, apricot, papaya, goji berries.
Vegetables include carrot, courgette, sweet potato, tomato, bell pepper, broccoli, cauliflower, fine beans.

Petals, Twigs, Bark and Leaves

Colour rich petals are a great hermit crab food source, you can harvest a lot of food from pesticide and fertiliser free sources for free and they will help enhance carapace colour. The whole dandelion plant can be used, rose petals, oak leaves and twigs, chamomile flowers, blackberry leaves, hibiscus flower, cork bark and choya/cholla wood. They provide much needed cellulose and tannins.

Nuts, Grains, Pulses and Seeds
Nuts are another source of protein plus other goodness and hermies go bonkers for them, they all seem to have an individual favourite but all natural peanut butter sends them completely mad. The fats also aid moulting.
Seeds like hemp, flax, sunflower and linseed. They love millet and millet sprouts so scattering it to sprout is excellent enrichment.
Pulses, lentils, soy beans, peas etc.
Grains like rolled oats, amaranth, wheatgerm and quinoa.
Peanuts, almonds, walnuts, cashews and brazils are the most common favourites.

Oils
Hermie safe oils can be drizzled over foods, salmon, cold pressed virgin coconut and cod liver are favoured by mine but there are a fair few that they can have and they aid healthy moults.

Colour boosters
Hermie colour can be enhanced greatly by diet and after each moult you often will see a difference depending what they have been fed. Astaxanthin (found in krill, red seaweeds and shrimp) is important for this, as is beta carotene and other cartenoids. Brightly coloured foods like bell pepper are rich in beta carotene and shellfish, squash, sweet potato, egg yolk and blueberries are some good cartenoid sources.

Other stuff
All natural honey and bee pollen, air popped plain popcorn, safe animal poo and earthworm castings can be offered as hermit crab treat foods. Popcorn is probably the ultimate hermit crab treat and the others all offer goodness and the treat factor. Hermies often eat a lot of poo in the wild and earthworm castings is a more palatable way to account for that, mine also get poo from my CB snails and American keepers sometimes offer moose poo.

Try to offer protein, calcium and some form of fruit, veg or plant matter daily, change things up as much as possible and give them stuff from each group regularly. They need variety and will stop eating a food if it is offered too often. Safe food lists can be found online, and a rule of thumb is avoid preservatives and stay natural.

Water

Hermit crab water needs to be treated with a decent dechlorinator and heavy metal remover to remove toxins that are harmful to them. They need a dish of both fresh and salt, preferably deep enough for them to fully submerge but with pebbles and ramps so they can climb in and out with ease even if they are the smaller tank members. The salt water should be made up with a good quality marine salt like instant ocean so that it contains all the minerals and trace elements that would naturally occur.

Moulting

Moulting is a nerve racking time for hermie keepers, especially as the crab gets older and the moults begin to span anything from a month or more. The first thing to remember is, don't dig them up! You might be tempted when they have been down a long time, but unless you know 100% something is seriously wrong you must intervene with digging them up prematurely can result in a lot of complications and lead to death.
Hermie safe oils, honey, bee pollen and high energy or calcium rich foods can be offered to potential moulters more often than normal to help prepare them.
Moulters release a smell which is attractive to other hermit crabs, and unfortunately sometimes a moulter will be dug up or attacked by another crab. Surface moulters and dug up crabs need to be protected, cutting the base off a large bottle and putting it around them so nobody can dig under and reach them is one option, or moving them gently into a small iso tank if you are not happy using the bottle method. Keep water within reach and food in case they decide to eat, and leave them in the dark undisturbed as much as possible. If there was bits of exo put what you can with them, they eat the shed exoskeleton to regain what was lost so it or calcium sourced need to be available. Crab carapace is a good option, or cuttlefish bone if carapace is not available. Make sure the crab is completely hardened and has had a couple of days extra to recover, then give them a gentle bath before reintroducing them to the main tank and monitoring them for a bit to make sure everything goes ok.

Handling

Occasional handling is fine once the destressing period has passed, starting off slow to allow them to get used to you and less nervous. Slow movements are key, and when picking them up don't pull at them if they are holding onto something. Put them onto your hand gently, keeping it as flat as possible to minimise the amount they are able to grip if they become frightened, and don't panic if they do pinch! They won't always, but even the most comfortable around humans hermie will sometimes be startled or scared and grip on. Don't try to pull or pry them off as this will potentially hurt them and will make them even more determined to grip on from fear, just keep your hand flat and let them relax in your own time. Hermit crabs have a very powerful and painful grip as they get bigger, which is another reason they are not a good child's pet.

Let them move around you/the surface and be careful not to let them fall or encounter anything harmful. Keep the trip out the tank short and put them back as gently as possible. Letting them see you won't harm them and taking the chance to check them over will mean they are more used to it if they need treatment for something in the future.