Hermit Crab Care: Everything You Need to Keep Hermies Happy and Healthy

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A beginner’s guide on handling, feeding, and housing the cutest crustaceans out there

Co-authored by Marshall Stephens and Eric McClure

Last Updated: August 23, 2024 Fact Checked

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Setting Up a Healthy Habitat

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Caring for Your Crabs

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Hermit crabs, affectionately called hermies, are phenomenal low maintenance pets. But low maintenance doesn’t mean no maintenance! These cute little crabs need an adequate habitat and plenty of supplies, and we’re here to cover everything you need to know to keep these critters happy and healthy. Read on to learn how to care for hermit crabs.

Things You Should Know

Hermit crabs are social and thrive in environments with multiple other crabs.
Keep the humidity at least 75% and the temperature 75–85 °F (24–29 °C) at all times to ensure your crabs stay healthy.
Fill your crab’s habitat with children’s playsand, cocofiber, moss, empty shells, freshwater, saltwater, and climbing toys.

Method 1

Method 1 of 2:

Setting Up a Healthy Habitat

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1
Get a glass tank that’s 10 US gal (38 L) for every 2 crabs. So, if you have 6 hermit crabs, they’ll need at least 30 US gal (110 L) of space. A proper home for your crabs should hold humidity but still let in fresh air, so a fish tank or reptile aquarium usually does nicely. You can even rinse out that old leaking tank from the attic and use it! Acrylic terrariums tend to work too.
- If the hermit crabs are on the larger size, opt for a bigger tank than necessary.
- Hermit crabs like having plenty of space, so bigger is always better with the habitat.
- You can theoretically even keep your crabs in a big plastic bin, if you’re really short on materials.
2
Maintain a humidity of roughly 75% at all times. Get a a hygrometer (humidity gauge) and stick it in the crabs’ habitat to track the humidity. Whenever the humidity gets too low, mist their cage with a little water. Hermit crabs breathe through hardened gills, and can't breathe properly unless the air is humid enough, so keep them moist at all times.^{[1]
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- A great way to increase your tank's humidity naturally is to add natural moss to your tank.^{[2]
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  Research source} It increases the humidity, and hermit crabs love to snack on it it.
- Damp crab sponges are also a great way to keep the humidity high in a hermit crab tank.
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3
Keep the temperature roughly 75–85 °F (24–29 °C) at all times. Hermit crabs are tropical animals who prefer warm temperatures. Attach a tank thermometer to your crabs’ home to monitor the temps. Use an under-tank heater designed for hermit crabs, or set the tank in a part of your home that stays perpetually warm, too.
- Heat damage is irreversible, and temperatures that are too low can slow down a crab's metabolism, so maintaining a stable temperature is essential.
4
Fill the habitat with a substrate of kid’s playsand or cocofiber. Hermit crabs are diggers, and they’ll spend a lot of time under or in the substrate you choose. As such, pick something fine and safe. Your two best options are the playsand designed for small children, coconut fiber, or a mix of the two. Cover the bottom of your tank with substrate.^{[3]
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- Many crabs also like to bury and even molt in damp reptile moss.
- Aim to keep the substrate depth 3 times the height of your biggest crab. So, if you estimate your biggest crab is 3 inches (7.6 cm) tall, keep the substrate 9 inches (23 cm) deep.
5
Set some climbing toys out for your hermit crabs. You may be surprised to learn that hermies love to climb! In the wild, they will climb large rocks exposed by low tide to search for food. Hermit crabs are sometimes called “tree crabs” because they’ll even climb trees to eat insects and vegetation. Just stay away from painted toys, since they can be toxic to hermit crabs.^{[4]
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- Natural rocks and seashells that you pick up at the beach are great to scatter around the crabitat. Clam shells even make great food dishes! Just make sure to boil them in boiling water so that they become sterilized before you place them in the tank.
- Plastic plants made for reptiles are great for crabs to climb and hide in. Just remember to use the lid of your tank so the crabs can't climb out.
- Never use reptile “half pine logs,” as pine is an irritant to the crabs and can be toxic.^{[5]
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Hermit crabs, like most animals, need a place to feel secure and hide when they feel threatened. You can use a half coconut shell that they sell at pet stores for small crabs, or use broken pots, large shells, etc. Just make sure that the crab won't get stuck inside.
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Add some live plants to your tank if you’d like. Live plants can be a great addition to any tank. In particular, plants like bamboo (make sure it's real bamboo and not Dracaena Sanderiana, which is sold as “lucky bamboo”), Venus fly traps bromeliads (air plants), pothos, and spider plants are among the other safe plants. Be forewarned--your hermit crabs may snack on them, so there's no guarantee the plants will have time to grow.^{[6]
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- You do not need to include live plants if you don’t want to; your hermit crabs will be just fine without them. They do provide some fun snacks for the crabs and add some beautiful decoration, though!
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Provide your hermies with clean freshwater and saltwater at all times. Provide at least two water dishes (one freshwater and one saltwater) for your crabs. Hermit crabs need to balance the salinity of the water in their shells; the dishes should be at least deep enough that your crab can get water in its shell. A good way to do this is to provide them with a sloping water area, where one part is shallow and easy to climb out of, while the other is deep and they can submerge themselves in the water.^{[7]
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- Never use tap water. Either use bottle spring water, or boil the tap water first before giving it to your crabs. The minerals and chlorine in tap water are bad for hermit crabs.
- For your saltwater, use salt designed for marine fish. Never use salt intended for human consumption because the anti-caking agents can be harmful. Aim for a ratio of 1.5 tsp (8 g) of salt for every 1 cup (1/4 L) of water.

Method 2

Method 2 of 2:

Caring for Your Crabs

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1
Replace the substrate every 6 months or so. Dirty substrate can lead to mold which can be harmful to your hermit crabs. Change it every 6 months or whenever their habitat starts to smell a little questionable. If you see mold or you spot a mite infestation, change the substrate ASAP. In between substrate cycles, spot clean any dung and food the crabs have dragged from the food bowl or buried.^{[8]
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- Never clean the substrate when your hermit crab is molting. You should never disturb or move a molting crab.
2
Handle your hermies with extreme care and patience. Hermit crabs normally get kind of twitchy when you touch them, so go slow. When you get your hermit crabs, leave them in the tank for a few days. Once your crabs don’t shy away from you, try putting your hand down near them to see if they’re interested. Let your hermit crab explore your hand and get used to you.^{[9]
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- Once you get them home, they go through a “de-stressing” period that can take as little as a few days and as long as two months. During this time, change out their food and water regularly and do not disturb them.
- Your crabs probably won’t like being held, but many hermit crabs will learn to tolerate handling if you go slow and you don’t make a lot of sudden movements.
3
Let your hermit crabs molt in undisturbed peace. If a crab digs under the substrate for a couple of weeks, don't worry. It’s molting! Do not disturb your crab during this time. They need to be alone and if they are bothered, the stress could kill them. A crab's exoskeleton gets tight as they grow, and molting is how they solve this problem. They shed their exoskeleton and grow a new one, so let them be.^{[10]
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- Don't take the exoskeleton away from the crab! They will need to eat it in order to harden their new exoskeleton when they’re done.
- If your crab behaves like they’re sick, don't panic. Keep an isolation tank in a closet with enough substrate to dig under completely and ample food and water. Crabs often act sick when they’re about to molt, so the odds are good they’re fine.
4
Set out multiple extra shells to give your crabs options. When hermit crabs grow, they look for bigger shells. Keep plenty of extra hermit crab shells similar to your crabs' sizes in the tank at all times; they’ll go around and look for new housing as they see fit. Once a month or so, rotate a few undisturbed shells out with different styles of shells.
- Purple Pincher Hermit Crabs prefer the shells with round, circular openings. They will choose circular openings over the oval openings. Ecuadorian Hermit Crabs will prefer an oval opening, because they have flatter abdomens.
- Only buy natural, sterilized shells—never buy painted shells! Although companies may claim the paint is safe, the paint can chip off, and if the crabs eat it, it can be toxic.^{[11]
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5
Feed your crabs a varied and healthy diet of hermit crab food. Hermit crabs are scavengers by nature and will eat almost anything. Provide a base diet of commercial hermit crab food. Any high-quality product will work so long as it’s designed for hermit crabs.
- Hermit crabs love fresh shrimp, freeze-dried krill, blood worms, and other seafood. You can normally buy these fishy foods at your local grocery store.
- If you cook, set aside a piece of steak or chicken, non-marinated to grill lightly for the crabs. They enjoy raw meat!
- If you have more than 20 crabs or so, get a fish head from a local fish market as an occasional treat.
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Offer fruits and veggies to your hermit crabs to keep them healthy. Aside from eating meat, hermit crabs also love different fruits and vegetables. Remember to change their food almost every day or night. Hermit crabs love to bury their uneaten food, and this can cause molding and is messy.^{[12]
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- Hermit crabs love fresh fruit like pineapple, apple, pears, grapes, cantaloupe, watermelon, mango, papaya, strawberries, bananas, etc. Wash your fruit thoroughly before you cut it, to avoid pesticides.
- Crabs will go crazy for coconut shavings!
- Hermit crabs will also eat natural peanut butter on whole wheat toast, hard boiled eggs, egg shells (boiled), and popcorn (plain, unsalted and unbuttered).
- Avoid anything from the Allium species of plants (onion, garlic, etc.).
While they generally pinch only when they are afraid or feel cornered, they may pinch for no reason, so don’t take it personally if your hermie gets a little snappy from time to time. If they pinch, just gently turn your hand over in the tank and let gravity gently drop the crab off of your hand.^{[13]
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Expert Q&A

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How can you keep hermit crabs you find at the beach?

Marshall Stephens
Aquarium Specialist
Marshall Stephens is an Aquarium Expert at Private Oceans Aquariums in West Palm Beach, Florida. Marshall has over 20 years of experience in the aquarium industry and focuses on captive-bred animals. They specialize in tropical and marine aquariums and are a contributor to the Loggerhead Marine life center in Jupiter Florida.

Marshall Stephens

Aquarium Specialist

Expert Answer

If it's a land-based hermit crab, you can care for it in a 10-gallon tank with a sand base, some hiding spots, some places to crawl around in, and a sponge soaked in water. To feed it, use pellets that are made specifically for hermit crabs. If it's a water-based crab, you can put it in your aquarium as a scavenger to hep keep the tank free of food that would otherwise sit around and cause water quality issues.

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I got a new hermit crab, but it won't come out of it's shell. What do I do?

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Don't do anything! It's normal for new hermit crabs to wait once they're moved to a new environment. They're just acclimating to their space and making sure it's safe to come out and explore. Give it a week or two and your hermie should be moving around like normal.

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What am I doing wrong? I have proper sand, fiber shavings, temperature control, shells, and I'm keeping the inside moist. I have still lost two. I have two water sources.(salt and regular) have 3 in a 10 gallon tank. Help!

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This answer was written by one of our trained team of researchers who validated it for accuracy and comprehensiveness.

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Did you buy your hermit crabs all at once from the same pet store? It seems likely that you just got unlucky and accidentally purchased some very old or very sick hermit crabs. Other than that, you mention fiber shavings. What kind of fiber is it? Crabs are sensitive to synthetic materials, so if you aren't using natural coconut shavings, that could be the culprit.

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Hermit crabs can't breed without special equipment, so feel free to mix male and female crabs in your tank. They can’t mate in captivity unless you put them in a colossal tank that simulates the ocean near-perfectly.^{[14]
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