Proper Care of Land Hermit Crabs

A care sheet written by hermit crab owner, Shadoe Haffner

This information is a compilation of opinions of what works for the majority of hermit crab owners, and may differ slightly from one crabber to the next. You should add this to your collection of hermit crab knowledge, and not take this as any authority care sheet.

Land hermit crabs can live for 30+ years! But only if they are cared for properly.

The Habitat

  • Space: For 2-3 small hermit crabs, a ten gallon glass aquarium is required as a minimum because more space is important for the crabs food/water/decor, and not just the crabs themselves. For 3 or more crabs, you will need a larger aquarium. Keep in mind that crabs will grow! As far as space goes, the bigger, the better! If you can afford a larger tank, get it. Crabs love to roam, and do best when they can get a lot of exercise in their tank. Even if you get 2 crabs and a ten gallon tank, eventually you will need to upgrade, as large and jumbo crabs need much more space.
    • You should also have an extra 10 gallon tank for emergencies if you need to isolate a crab in the future.
    • I would not advise keeping jumbos in anything less than 50 gallons. They are quite large and love a lot of space. You also will need about a foot of substrate to accommodate their digging and molting.

Our 55-gallon crabitat. Note the deep substrate, lots of climbing areas, large pools, etc.

  • The tank: A glass or acrylic aquarium is important to have. Pet stores, and even stores such as Wal-mart sell aquariums. You may even find them through garage sales, ads in papers, and local internet listings for a good price. Make sure you have a lid that can keep in moisture. If the lid is mesh, you want to cover most of it with Plexiglas, regular glass, or plastic wrap to keep in the humidity and heat.
    • Not acceptable: Plastic rodent-type cage or “kritter keeper” – Does not allow for enough room, does not hold in humidity.
    • Not acceptable: Wire cage – Does not allow for enough room, does not hold in humidity, doesn’t allow for deep substrate, can damage the legs of the crabs.
  • Location: Crabs like the quiet. You should try to place your tank in a low-traffic spot in your house away from any noises. You should also avoid placing the tank next to windows, heaters, and places where you use chemicals a lot. Windows and heaters may mess up the temperature of the tank. If the tank is near chemicals, they may drift into the tank and harm your crabs. You want to have your crab tank in a quiet, stable environment.
  • Substrate: Hermit crabs need to be able to create burrows under the ground in order to molt and grow. There are two commonly acceptable substrates that allow them to do this safely. The first one is play sand or all-purpose sand that can be purchased at your local hardware store. The second is Eco-Earth coconut fiber which can be purchased at the pet store or online. You can also buy both and mix them together, which seems to be the greatest preference among crab enthusiasts.
    • You want to make sure that you wet your substrate with dechlorinated water to sand-castle consistency. This means damp, but not wet.
    • You also want to make sure that your substrate is 2-4 times as high as your largest crab. A good minimum in any tank is 6 inches.
    • Not Acceptable for substrate:
      • Dry sand or coconut fiber- Does not allow the crabs to dig, can dry the crabs out. Wet the substrate.
      • Soupy substrate- Stagnant water can drown the crabs and promote the growth of mold and bacteria.
      • Shallow substrate- Does not allow the crabs to burrow and molt.
      • Gravel- Does not allow the crabs to burrow and molt, can get stuck in crab’s shell and cause pain.
      • Calci-sand, aragonite sand, reptile sand, hermit crab sand- Can harbor bacteria and stinks, is often dyed, can harden.
      • Any artificially colored substrate- The dyes used can be toxic to the crabs.
      • Wood chips- Does not allow the crab to dig, can be toxic to the crabs.
  •  Décor/stimulation: Hermit crabs need places to climb and explore as well as hide and relax. It is important to have many different hiding places. They are social creatures, but enjoy their alone time just as well. Crabs like open areas as well as jungle areas, so try to provide both if you can.
    • Acceptable climbing/hiding items:
      • Fake plants or approved real plants
      • Cholla wood
      • Resin decorations designed for fish tanks or reptiles
      • Fake or real driftwood
      • Fake vines
      • Branches from safe trees
      • Nets and hammocks
      • Coconut huts
    • Not acceptable for climbing/hiding:
      • Anything with paint that is chipping off- Crabs may eat paint chips and become ill.
      • Unknown types of wood. If you don’t know what kind of wood it is, leave it out! Check the “safe food list” at the end of this care sheet to learn what is safe, and what isn’t.
      • Moldy items- Keep an eye on any wood you may have in the tank. It will sometimes become moldy. The white fuzzy mold is usually harmless, but some may have allergies.
  •  Cleaning: It is good to spot clean your tank daily for moldy food that the crabs may have hid, or poop that is piling up in one spot. The tank only needs to be deep cleaned every 4-12 months depending on the size of your tank.
    • Try to schedule a deep clean when all or most of your crabs are above ground and not molting.
    • To do a deep clean, follow these steps:
      1. Remove the crabs and place them in a container or tank with very high walls and places to hide.
      2. Remove all the décor.
      3. Slowly remove the substrate and place it into bags to be discarded. Watch out for buried crabs. Any crabs that you find that are molting need to be placed into your extra 10 gallon tank. To set up an isolation tank for molting crabs, refer to the Surface Molting section in this care sheet.
      4. Scrub the tank with vinegar or bleach, rinse with water thoroughly, and dry.
      5. Replace the substrate.
      6. Wash the décor, water dishes, food dishes, and place it back in the tank. If you have had pest problems in your tank, you want to bake any wood you may have. Do this by wetting it thoroughly and baking it at 200 degrees for about 20 minutes, checking it constantly to make sure it’s not burning. You can also boil the items. I prefer to boil my items.
      7. Get the temperature and humidity at or near the normal (see Environment section in this care sheet).
      8. Place crabs in the tank.
      9. Leave them alone for a week to settle in and de-stress.
    • Some crabbers choose never to do deep cleans, and instead just replace the top layer of substrate. This is fine.

Environment

  • Temperature: Land hermit crabs are form near the equator. The temperature there is fairly constant year-round. The best temperature to keep your tank at is 80 degree Fahrenheit. This can be achieved easily with a heat lamp, heat mats, or a ceramic heat emitter. Make sure you have a thermometer in the tank to monitor the temperature. Do not let it dip below 70 or above 90. If your tank is large enough, it is good to have a hot end and a cool end of the tank. Your hot end may be in the 80’s and your cool end, in the 70’s.
  •  Lighting: You may want to provide your crabs with UV lighting from the top of their tank. This can help with the temperature, and  may be beneficial for the crabs in that it sets up a night/day cycle if they don’t get much natural light.
  •  Humidity: Land hermit crabs need a moist environment because they breathe through modified gills. The humidity is best kept around 80%.
    • You should purchase a hydrometer or two to put in the tank to monitor the humidity.
    • Do not let it dip below 70 or above 90. Below 70, they will slowly suffocate, and above 90, they may develop bacterial infections.
    • Fluctuations around 80% in humidity are fine, and expected with the changing seasons.
    • Tips to boost humidity: If you live in a dry place, you may want to use or at least include Eco-Earth coconut fiber as your substrate because it retains moisture very well. You can purchase a spray bottle and fill it with dechlorinated water to spray in the cage when the humidity dips. It also helps to have a moss pit, and bubblers in your pools.
  •  Air Flow: It is important to provide a fresh air intake to your tank. You can achieve this in several ways. The easiest way is to just take off the lid of your tank for a few minutes every day. Another way is to have bubblers in your pools, as they pull air from outside the tank. You need two pumps, two air stones, and aquarium tubing to achieve this. A more advanced way is to install computer fans to deliver a constant breeze in your tank.

Food

  • Fresh fish, rose petals, starfruit, and nasturtiums.

    Food: Hermit crabs are scavengers and their diet as based on variety. You want to avoid products labeled “hermit crab food” because they often do not provide adequate nutrition, can contain harmful chemicals and preservatives, and you will be feeding the same thing every day, which crabs don’t enjoy. In the wild, it has been shown that the crabs avoid recently eaten food, and have preference for as much variety as possible.

  •  Hermit crabs love fresh fruits, vegetables, cooked or uncooked unseasoned meats, nuts, and seafood. While you or your guardians are preparing dinner, set aside some of the veggies or meat for the crabs. You can also dehydrate or freeze these foods to feed later. There are also a couple stores online that offer different safe dehydrated food mixes if you are unable to provide fresh foods all the time. If you know what to look for, you will also find that your crabs may be able to eat many things in your backyard such as dandelions. Make sure that if you harvest your own food from outside, it is safe for crabs, free of pesticides, fertilizers, and pollution. A full “safe foods” list can be found online. The link will be provided at the bottom of this care sheet. You should change the fresh food every day. The dry food can be changed every 1-4 days. The crabs do not eat a lot, so there might not be any evidence that they eating at all, but they are. Since crabs also like a variety of food. It’s good to give them different things with every food change.
  • Short list of common unsafe food:
    • Garlic
    • Onions
    • Citrus peels
    • Chemicals
    • Preservatives including salt (though, table salt is ok in moderation)
    • Added sugars
  • A full unsafe foods list can be found online and the link will be provided at the bottom of this care sheet.
  • Hermit crab eating crushed oyster shell for calcium.

    Supplements: As well as fruits, veggies, and meats, hermit crabs also need supplements. The main supplement they need is calcium. You can purchase powdered cuttlebone at any pet store, online, or you can crush up egg shells and offer it to them in a dish. They will also munch on whole cuttle bone, and crushed oyster shells. I have found that my crabs like the oyster shell best. You can also use exoskeletons from other crustaceans. My crabs also love to munch on the carapaces of king crabs.

  • Crabs also like to eat animal feces. You can purchase worm castings online or you may be able to find it in the garden sections of stores. They also like other kinds of feces, but be careful when feeding it to them, as it can contain high numbers of bacteria. Always wash your hands after touching feces. They like to eat tortoise poop, bird poop, and cattle poop in the wild. Do not feed any unknown poop or poop that came from an animal that has been treated for worms or any other sickness.
  • There is also a mineral supplement available through one online store that the crabs go crazy for. A link will be provided for “The Hermit Crab Patch” at the end of this caresheet.

Water

  • Hermit crab surveying her fresh and saltwater pools.

    Fresh water: Hermit crabs need fresh water to drink, bathe themselves in, and keep in their shells. The water dishes need to be deep enough for all of your crabs to fully submerge in (or at least most of the way), but easy enough for them to escape from. Plastic food storage containers are great for this. You can use silicon glue and Plexiglas to make a ramp, or you can use branches other décor to give the crabs an escape route. Please see my tutorial on how to make pools for your crab tank. All water that goes into the dishes and tank needs to be dechlorinated! Dechlorination supplies can be found at any pet store in the aquarium section or online. It may be possible to use water from a well, river, or stream if you are 100% sure that the water is not contaminated. You will want to get the water tested for chemicals and heavy metals before giving it to the crabs. If you are not 100% sure, dechlorinate! Another safe water source is bottled spring water. But please recycle the bottles.

  •  Salt Water: In the wild, land hermit crabs have access to salt water and need a supply of it to drink, bathe themselves in, and keep inside their shells. Just like the fresh water, the dishes need to be deep, escapable, and dechlorinated. The salt used to make salt water for hermit crabs is not regular table salt. It is necessary to purchase marine aquarium-grade salt used to make salt-water aquariums. You will probably want to buy in bulk to save money. “Hermit crab salt” is not salty enough, only comes in small containers, and does not contain most of the minerals found in marine salt water. Marine aquarium-grade salt can be found at any pet store or online. The water, if stagnant, needs to be changed every 1-3 days. If you have filtered or aerated pools, change the water every 4-14 days whenever the sides become slimy or the water becomes cloudy. Make sure to scrub the dishes or pools thoroughly with hot water.
  • Some crabs like to submerge themselves completely and may stay underwater for several minutes at a time.

    Not acceptable for water:

    • Sponges- Not a sufficient amount of water, perfect place for bacteria to grow, crab cannot replace shell water with a sponge. Sponges are simply a gimmick created by the pet industry. You hermit crab has no use for a sponge.
    • Straight tap water: contains chlorine, and possibly heavy metals.
    • Rain water: May have collected chemicals from the air depending on where you live.
    • Shallow dishes: Does not allow for the crabs to bathe properly.
    • Pools with no escape route: Crabs may fall in and drown.
    • Salt water made with table salt: Can contain chemicals that can kill the crabs, does not have any minerals.
    • Salt water made with “sea salt” or fresh water aquarium salt: Does not contain the minerals sea water would have.
    • Dirty water: Crabs may end up sick from drinking it, or get dehydrated from refusing to drink dirty water.

Shells

  • You can never have too many shells for your hermit crabs to choose from.

    Shells: It is necessary to provide at least three different properly-fitting shells per crab to change into as well as a couple more for them to grow into. There are preferred shell guides available through my site and on the Hermit Crab Association website. It is important to offer natural shells only to your crabs. Natural shells can be purchased online, at pet stores, or various stores such as Hobby Lobby, Michaels, Wal-mart, etc. Please see my article for an in depth look at why painted and decorated shells should be avoided.

  • Unacceptable shell choices:
    • Painted shells: The paint can chip off, and your crab, being a scavenger, may eat the chips. The paint might be non-toxic, but that is just to humans. The paint may be toxic enough to poison your crabs. No painted shells are proven safe.
    • Decorated shells: Shells with hats or other things glued to them can weigh down the shell of the crab or get caught on things in your cage. The glue used might also be toxic.
    • Not enough shells: If you don’t have enough shells for your crab to choose from, they might become stressed about wearing a shell they don’t like and attack tank-mates to get their shells.
    • Not the right type of shells provided: The crab might become stressed about wearing a shell they don’t like and this may also result in a shell fight among tank-mates.

Molting

  • Hermit crab molting underground. Picture taken through the bottom of the tank.

    Molting: Hermit crabs need to molt in order to grow. This process is stressful for the crab, so it is important to understand the process and the needs of the crab while undergoing it. The crab will dig down under the substrate, shed it’s exoskeleton, eat it, and re-grow a new one. During this process, you need to avoid digging in the tank.

    • You should never dig up a crab whether it’s molting or not.
    • Molting crabs also like it dark. If your crab is molting against the glass, avoid shining a flashlight in there…it’s tempting. You may want to even tape a piece of dark paper over the window.
    • Molting crabs also like quiet. Avoid tapping the glass or unnecessary tank movement.
  • Make sure your non-molting crabs are being fed plenty of protein and calcium at all times in order to avoid cannibalism.
  • It can take anywhere from a week to several months for a crab to finish molting. Smaller crabs take less time, while jumbos have been known to take several months. Remember the #1 rule: DO NOT DIG! Let nature do it’s thing.
  • Two 10-gallon isolation tanks.

    Surface molting: If your crab decides to surface molt (molt above ground), steps need to be taken to make sure it is successful. If you see a limp crab, but it does not smell like dead fish, it may not be dead! It may just be surface molting. Do not assume your crab is dead until it smells like dead fish and does not move for at least 24 hours!

    1. Ready your extra 10 gallon tank
      • Moist substrate
      • Proper heat humidty (80F, 80%)
      • Dish of fresh water
      • Dish of salt water
      • Dish of food
      • Dish of calcium source
      • Place for crab to hide
    2. Place the crab, and the exoskeleton if it’s already been shed, in the tank under the hide (or if you don’t have an extra hide, place a cloth over the tank to keep it dark).
    3. Put the tank in a dark, quiet, stable spot and try not to bother the crab.
    4. Wait (this could take up to several months).
    5. When the crab is up and walking around the tank, only then is it okay to put it back in the main tank.

The Crabs

  • Hermit crabs are very social and should never be kept alone.

    Choosing crabs at the pet store: You want to make sure that you are buying healthy crabs. You should be able to hold them at the pet store. Check that they are alive, active, free of mites, and not missing a bunch of limbs. Despite their name, hermit crabs are very social animals and should never live alone because they will become stressed. Buy at least two crabs. After a while, if you feel comfortable with your two crabs, and ready for more, go for it! But remember that you will need a tank larger than 10 gallons for any more than 3 small crabs.

  •  Bringing a crab home: If you have a long drive home, you may want to bring a plastic or glass tank with moist substrate in it to transport them in. Often, pet stores will give you cardboard containers that are void of any humidity, and hermit crabs have been known to escape from such containers if given enough time. When you arrive home, ready three dishes. One salt water, one fresh, and one empty with high sides, and a towel at the bottom. You are going to bathe your crabs to check for mites. You want to submerge your crabs for a few seconds in the salt water one at a time and then submerge them in the fresh water for a few seconds. Then place them in the towel container to dry off. Check the water for mites (they will be floating on top). If the water is mite-free, check the crabs. If they are mite-free, they can be placed into the main tank.
  •  Introducing new crabs to your colony: Once they are in the main tank, the other crabs will sort out a pecking order with them. This is natural and should be allowed to happen. The old crabs will jump on the new crab. Only break up the “fight” if it starts getting rough (pinching of limbs).
  •  PPS: PPS stands for post purchase stress. The hermit crabs have traveled a long way to the pet store, and sometimes coming home to another new environment stresses them out too much, and they die for various reasons. To avoid this, wait at least 2-3 weeks to touch or play with your new crabs. It’s best to wait until after their first molt, however. They need to de-stress and get used to their new environment before they will be able to take a big scary giant handling them.
  •  Holding your crab: When you pick up your hermit crab, you want to do so by the back of their shell. Then sit down on the floor or soft surface and place them in your other hand. Make sure your hand is completely flat so that if your crab gets scared, it won’t be able to pinch your skin. Once you and your crab get to know each other better, you might be able to hold it in your hand without having it flat. The most important things to remember are to be near the floor or other surface in case the crab falls, and to be still so that the crab feels stable. Make sure that you don’t pick up the crab unless it is already being active in the tank. Picking up a sleeping crab may make it more inclined to pinch you and it stresses the crab out to be woken up.
    • Some crabbers choose a more hands-off approach. For me, it depends on the individual crab. Some don’t mind being held, and others will pinch you any chance they get. You have to learn to read their body language, and that takes time. Out of my 20-something crabs, I only have 3 or 4 that I take out and hold at all, and only 1 that I hold regularly. Most would rather stay put in the tank.
  • Hermit crabs may enjoy some time outside if the conditions are not too different from their tank.

    It is fine for you to take your crabs out of the tank a couple times a week for 10-45 minutes at a time to wander around a room or bed. It is important to make sure that the crab you want to take out is already up and moving around before taking it out. Make sure the temperature and humidity of the house or room they are in is not drastically different from their tank. If the temp is below 70, avoid taking the crabs out. If the humidity is below 40, also avoid it. Make sure there are no chemicals where you have the crabs. You also want to watch to see that the crabs aren’t eating things they shouldn’t be. The crabs pick at carpet fibers or find little bits of old food. Make sure they don’t do this. If you have other pets around, make sure they are not harming the crabs. You can also take the crabs outside. You want to make sure that again, the temperature and humidity is not drastically different. You also want to make sure that there are no chemicals, fertilizers, or harmful animals. Do not leave them in direct sunlight for long. Their shell is a bit like a greenhouse. Shade is best.

  • If you live in a warmer climate, you may find it fun to make an extra outdoor enclosure where the crabs can get more exercise. Use common sense when building and using this enclosure. Crabs are escape artists, so the walls will need to be smooth and high, or put a ceiling on it. You may want to also have the walls extend to under the ground because crabs will dig their way out, too. Avoid putting this enclosure in direct sunlight, as that may dry out or overheat the crabs. Make sure they have food and water, and make sure the outdoor temp and humidity closely match what is in your tank.

DO NOT:

  • Take out sleeping crabs- This stresses them out and may make them more inclined to pinch.
  • Place the crabs on a high surface above a hard floor- They might fall and die.
  • Drop the crabs- They could suffer injury
  • Allow the crabs to eat things you are unsure of- They could eat something harmful
  • Stick your finger in its claw- It’s a reflex to pinch

Pinching:

  • Hermit crab pinching my hand flesh out of curiosity. He wanted to know what I tasted like.

    Usually, a crab won’t pinch you unless it feels it needs to hang on to avoid falling. If you get pinched, the best thing to do is be very still. If it is pinching your hand, place your hand on the floor or in the tank, and stop moving. The crab will feel stable and likely let go. Occasionally, you will get a curious crab that is comfortable being held, and he/she may want to see what you taste like. This type of pinching usually doesn’t hurt, but you can discourage the crab by blowing on it softly.

DO NOT:

  • Run your crab under hot water
  • Try to pry the crab off
  • Hit or fling the crab
  • Burn the crab with fire (yes, this has happened)

Bathing your crabs:

  • Some people find it necessary to bathe their hermit crabs, but others feel it adds unnecessary stress and messes up the salinity of their shell water. If you have deep enough water dishes, the crabs will bath themselves. It is not necessary to bathe your crabs as long as they have deep enough water dishes.

Habits of the crabs:

  • Hermit crabs are nocturnal. Their most active time is between two and four a.m., which makes them hard to observe. You can modify the time they emerge from their daytime slumber by making it dark earlier, feeding smelly foods, or both. If you make their habitat dark by eight p.m., they should be out about nine or ten p.m.

Helpful Links

For up to date hermit crab information, emergency help, or to ask general questions, go to:

Hermit Crab Association

For safe food mixes, shells, water treatment, and décor, go to:

Hermit Crab Patch

Hermit Crab Addiction Store

For shells, and décor, go to:

Pet Discounters

For a list of safe food, go to:

HCA Safe Foods

For a list of unsafe food, go to:

HCA Unsafe Foods

For the HCA preferred shell guide, go to:

HCA Preferred Shell Guide

For the HCA bug guide, go to:

HCA Bug Guide