Hermit Crab Supplies & Care Guide

Hermit crabs are sold everywhere — beach shops, pet stores, checkout lanes — usually in a painted shell, in a small plastic cage with a sponge and a dish of dry food. They look like a simple, cheap, low-fuss pet. They are not, and that mismatch is why so many pet hermit crabs die within weeks or months of coming home. It is almost never the crab's fault. It is the housing. A land hermit crab breathes with modified gills (breathing organs that only work while they are damp), so a dry cage slowly suffocates it. Given the right setup, though, these same little animals can live 10 to 15 years or more, dig elaborate tunnels, climb like tiny mountaineers, switch shells with great ceremony, and show a surprising amount of personality. They are social, curious, and endlessly watchable once the lights go down. This guide is written honestly and kindly, because you deserve the real picture and your crabs deserve a real chance. Read the Quick Start first, get the tank running a full day before anyone moves in, and keep this guide handy. Humidity and shells are the two things that matter most.

Quick Start: Your First 48 Hours

1. Set up the complete tank before your crabs arrive. Use a glass aquarium with a tight-fitting lid — 20 gallons is the minimum for 2 to 3 small crabs, and a 40-gallon breeder is better for a larger group. Place it in a quiet room away from drafts, heating and cooling vents, and direct sun. Plan from the start to keep at least two or three crabs, because they are social animals and a single crab is a lonely one.
2. Build the substrate (the digging layer) first. Mix play sand and coconut fiber at about 5 parts sand to 1 part coconut fiber, then dampen it with dechlorinated water until it holds its shape like wet beach sand. A dechlorinator is a water conditioner that removes the chlorine and chloramine in tap water, both of which harm crabs. Pack the mix to a depth of about 6 inches, or at least 3 times the height of your tallest crab, whichever is deeper.
3. Install a heater on a thermostat and a digital thermometer, and verify the numbers. Aim for 75–80°F in the warm zone with a slightly cooler zone at the other end, and never let the tank fall below about 70°F. Use a tank-wall or under-tank heater controlled by a thermostat. Skip heat lamps, which dry the air. Let it run for 24 hours before any animal goes in.
4. Get the humidity working before the crabs arrive. Place a digital hygrometer (an instrument that measures moisture in the air) at crab level and aim for 70–80%. Damp substrate, a tight lid, and two water pools will get you there. Do not trust the little dial gauges that come in kits; they can be well off the true reading.
5. Set up two water pools, one fresh and one salt. One shallow dish holds dechlorinated fresh water. The other holds marine salt water made with a salt mix designed for saltwater aquariums (never table salt, and no iodine). Both need a ramp, stones, or a sponge so every crab can climb out easily.
6. Lay out spare shells. Offer at least three natural, unpainted shells per crab in a range of sizes, with openings slightly larger than each crab's current shell. A crab that cannot find the right new shell is a stressed crab.
7. Add things to climb and places to hide. Cholla wood, driftwood, and cork bark give crabs exercise, shade, and security. Put at least one hide per crab.
8. Offer a small first meal in the evening. Hermit crabs are most active after dark. Put out a few fresh bites of a safe food (a sliver of carrot or mango, a pinch of quality pellets), a piece of cuttlebone for calcium (the mineral crabs use to build and harden their outer shell), and make sure both water pools are full.
9. Let the crabs settle for several days, and do not dig them up. New arrivals often tunnel under the surface for days or even weeks. This is normal stress recovery, and sometimes the start of a molt (when a crab sheds its hard outer skeleton, called an exoskeleton, and grows a new, larger one). A buried crab is almost always fine. A dug-up crab is not.
10. Clean your hands and your home, and line up help. Wash hands before and after contact with the crabs or the tank. Keep aerosols, air fresheners, paint fumes, and cleaning sprays away from the room. Write our number, (717) 983-8069, on a sticky note by the tank, and look for an exotic-animal veterinarian in your area now (see "When to Ask for Help" below).

First-Time Starter Bundle

What needs to be in the house on day one, and what to look for in each category.

Essentials

• A glass aquarium with a tight-fitting glass or acrylic lid — 20 gallons for 2 to 3 small crabs, 40-gallon breeder for larger groups. Glass holds humidity and heat; mesh tops and plastic "crab cages" let both escape.
• Play sand — plain, washed, unscented, undyed, with no additives. The main body of the substrate.
• Coconut fiber — loose, plain, chemical-free fiber sold in compressed blocks or loose bags. It holds moisture and gives the sand its tunnel-building strength.
• A tank-wall or under-tank heater with a thermostat — sized to the tank, so the temperature is held steady without a heat lamp.
• Two digital thermometers — one at the warm end, one at the cool end, with probes if possible.
• A digital hygrometer — placed at crab level, away from the water pools. This is the single most important gauge in the tank.
• Two shallow water dishes — heavy, non-metal, and large enough for the biggest crab to dip into, with gentle ramps or sponges for exit.
• A water dechlorinator — for conditioning tap water used in the fresh pool and for dampening the substrate.
• A marine salt mix made for saltwater aquariums — free of iodine and added copper, for the salt pool.
• A varied collection of spare shells — natural, unpainted, and cleaned, with several sizes and opening shapes per crab.
• Quality hermit crab pellets — free of copper sulfate, artificial preservatives, and ethoxyquin.
• A calcium source — cuttlebone and/or crushed oyster shell, always available.

Ready to set up? Browse the essentials in our collections: Hermit Crabs.

Enrichment

• Cholla wood, driftwood, or branches — for climbing, with stable placement that cannot shift or collapse.
• Cork bark pieces and half-logs — secure dark hides at ground level and higher up.
• Natural rope or coconut-fiber climbing structures — for exercise and exploring.
• Safe live or artificial plants — to add cover and hold humidity, free of pesticides.
• Leaf litter — dried, pesticide-free fallen leaves for foraging and cover, plus coconut halves and seeds.
• A small spray bottle or fine mister — used only with dechlorinated water for topping up moisture around the tank.
• A background on the back and sides — helps the crabs feel sheltered and reduces light stress.

Meet Your Hermit Crab

The hermit crabs sold as pets are land hermit crabs of the genus _Coenobita_. In the wild they live along warm tropical coastlines — on beaches, among dunes, and in the shady forest edges just inland — where they scavenge fallen fruit, leaves, seeds, driftwood debris, and anything else edible they can find. They are omnivores (they eat both plants and animals), and they are not related to the saltwater hermit crabs sold for aquariums, which live entirely underwater and cannot survive in a land setup. Land hermit crabs need the sea only in one way: females must return to the ocean to release their young, which is why hobby breeding is not realistic and why every pet crab you meet was born in the wild.

The species you will meet

Caribbean hermit crabs (the "purple pinchers") are the most commonly sold. They have a distinctive purple-tinged large claw and a hardy, bold temperament. Ecuadorian hermit crabs are slimmer and often paler, with a more active, climbing-oriented personality. Strawberry hermit crabs are the largest of the three, with bright red-orange bodies and a love of climbing; they need more space than their cousins. Pet stores often label species loosely, so a crab sold as one kind may turn out to be another. The good news is that all three need the same basic care: warmth, high humidity, deep substrate, salt and fresh water, and a varied diet.

Social life and the nocturnal rhythm

Hermit crabs live in groups, and a group of crabs will huddle, share shells, follow each other around, and communicate by tapping and posturing. A crab kept alone often hides, eats less, and fades. Keep at least two or three together, and give them enough room to avoid constant squabbles over food, water, and shells.

They also keep night owl hours. You may rarely see them in the afternoon, then come downstairs at midnight to find the whole tank in motion — digging, climbing, feeding, and swapping shells. A dim room and a natural day-and-night cycle (about 12 hours of room light and 12 of darkness) let them keep their own rhythm. If your crabs are all hiding during the day, that is normal, not a problem.

The lifespan reality — honest and kind

Here is the truth. Hermit crabs in the wild commonly live for decades, and with excellent care in captivity, 10 to 15 years is a reasonable expectation, and some live considerably longer. Yet most crabs sold as pets die within weeks or months, because the cages they are sold in are too small, too dry, too cold, and equipped with painted shells and sponges. If a crab dies in your care, please do not blame yourself too quickly. Many are already stressed, dehydrated, or weakened when they reach the shelf. Go back to the basics in this guide, give the survivors what they need, and learn from it. The difference between a short life and a long life is almost entirely housing.

Wild-collected animals and responsible keeping

Nearly all pet hermit crabs are wild-collected. That is not a reason to avoid them, but it is a reason to take them seriously. Adopt only as many as you can house well, buy from sellers who keep their crabs in good conditions, and give each animal the best possible care. A crab that survives for a decade is a small conservation win and a great companion.

What surprises new owners

Three things catch most new crab owners off guard. The first is how much they dig. Crabs spend much of their time underground, and a tank with no visible crabs is often a healthy tank. The second is the molting: a crab can disappear for weeks or months and come back larger, brighter, and hungry. The third is how much they need to climb and explore. An empty tank with a sponge and a dish is a prison. A deep-sand, climbing-and-hiding habitat is a world.

Enclosure Setup & Layout

Tank size and type

Choose a glass aquarium with a tight lid (glass or acrylic, with a small gap or vent for fresh air). Glass holds humidity and heat; screen tops let both escape, and hermit crab "cages" made from plastic with mesh sides and paint-based décor are the single biggest cause of early death. If you have a mesh top, cover most of it with acrylic or glass. Crabs are strong climbers and escape artists, so make sure the lid sits firmly.

The layout, front to back

Think of the tank as a small stretch of beach, a shaded forest edge, and a rocky outcrop, all in one box. If you were drawing a labeled diagram, these are the zones:

A. Substrate (floor): a deep layer of damp sand and coconut fiber, about 6 inches deep or at least 3 times the tallest crab's height. Slope it slightly so one side is a bit deeper for digging. Crabs need depth for burrowing and molting, so do not skimp.

B. Warm end (left side): the side where the heater sits on the outside of the glass, on the back or side wall. Aim for the warm zone at 78–80°F. Place a cork bark hide here so crabs can warm up in shade.

C. Cool end (right side): around 72–75°F. Put a second hide and the main climbing branch here so crabs can cool off or go higher to sit in warmer air.

D. Fresh water pool (back left): a shallow, heavy dish of dechlorinated fresh water sunk into the substrate so its rim sits at floor level, with a ramp of stones or a sponge.

E. Salt water pool (back right): a second shallow dish of marine salt water, sunk and ramped the same way. Keep the two pools separate and use a separate tool to clean each.

F. Climbing structure (center and back wall): cholla wood, driftwood, and rope anchored so nothing can tip. Make climbing routes that run from the floor to near the lid, with crabs able to rest on branches at different heights.

G. Feeding station (front): a flat, shallow dish or rock for food, placed away from the pools to keep them clean. A second dish for calcium (cuttlebone and crushed oyster shell) sits beside it.

H. Shell shelf (front right): a corner or low area where spare shells are laid out in a gentle scatter. Crabs love to inspect them at night.

I. Hides and background: cork bark tubes, half-logs, and coconut huts at ground level and a little higher. Cover the back and sides of the tank with a dark or natural background so the crabs feel sheltered.

Add a layer of leaf litter across part of the surface for foraging and cover. Build the layout so there is open floor to walk across, plenty of shade, and nothing the crabs can topple.

Substrate Guide

Substrate is not just bedding. It is where your crabs live, dig, hide, and molt, and its moisture is part of how the tank holds humidity. The ideal mix holds a tunnel when damp (a texture keepers call sandcastle consistency): when you squeeze a handful, it should hold its shape without dripping, and when you dig, the walls should stay up.

Avoid outright

• Cedar, pine, and any aromatic wood shavings
• Calcium sand or "reptile sand" with added minerals
• Gravel, coarse pebbles, or crushed coral as the main floor
• Fertilized or pesticide-treated potting soil
• Dyed, scented, or glittery sand
• Sand collected from a beach or garden
• Cat litter of any kind

Keeping substrate healthy

Mix new substrate with dechlorinated water in a bucket before it goes in the tank. Moisten it fully, then squeeze it to check the texture. Each day, spot-clean droppings, uneaten food, and anything that looks moldy. Every month, stir the top few inches lightly to check for sour smells, and never stir deeply when you know a crab may be buried. Replace the top layer if it smells bad, and plan a full substrate change only when the entire group is above ground and no crab is molting.

Heat & Humidity — The 3 Numbers

Land hermit crabs come from warm, humid shorelines, and they rely on the tank to keep two things in a narrow range: temperature and moisture. Of the three numbers that matter most — temperature, humidity, and water quality — humidity is the one that decides life and death. Those modified gills only work while they stay damp, so dry air slowly suffocates a crab, often with no obvious warning until it is far gone.

Temperature — heat from the walls, not the lamp

Heat the tank gently from the side or back wall. A stick-on or under-tank heater on a thermostat (a device that switches the heater on and off to hold a set temperature) keeps the air warm without drying it. Put the thermostat probe at crab level. A heat lamp is the wrong tool for hermit crabs: it dries the air and can overheat a shell sitting in its beam. If you use an under-tank heater, keep it to one end and cover only part of the base, so the burrowing crabs can always move away from the heat. Check the thermometers every day, particularly in winter and during heat waves.

Humidity — the number you must measure

A hygrometer is the only way to know your humidity. Choose a digital one and place it at crab level, away from direct spray and the pools. To keep humidity at 70–80%, use all of these together: a tight lid, damp (not wet) substrate, two open pools, and a light misting with dechlorinated water. A small amount of damp sphagnum moss on the surface also helps.

You can test your hygrometer: seal it in a small airtight container with a bottle cap of damp table salt (never near the crabs) for several hours; it should read about 75%. Table salt is fine for that test only, never for the salt pool.

Water — two pools, always

Crabs use both pools. Fresh water is for drinking and bathing. Salt water is a mineral supplement they sip and use to refill their shells. In the wild, crabs dip into both. Salinity is the saltiness of water. Marine salt mixes made for saltwater aquariums are blended to match seawater, so follow the package directions and mix the salt in a clean container of dechlorinated water. Never use table salt, which often has anti-caking agents and iodine, and avoid mixes that contain added copper. Pools must be shallow, with a ramp or sponge so even the smallest crab can climb out, but deep enough that the largest crab can dip its shell. Change both daily or every few days and scrub them weekly.

Diet & Nutrition

Hermit crabs are omnivorous scavengers: in the wild they eat fallen fruit, rotting wood, leaves, seeds, coconut, dead fish, insects, and whatever washes up. That variety is the point. A crab fed only a dish of dry pellets is like a person eating only crackers. Aim for a small, mixed buffet each evening: a quality pellet base, fresh vegetables and fruit, a protein bite, and calcium that is always available.

No mystery ingredients matters here more than almost anywhere. Cheap hermit crab foods often carry copper sulfate (a copper-based preservative toxic to crustaceans), artificial preservatives, and ethoxyquin, so read every label. Clean Fuel, No Junk is how we feed our own animals, and the same rule applies to the crab dish: plain, fresh, and honest.

Safe foods

Foods to avoid

Calcium — building and hardening the shell

Calcium is the mineral a crab uses to build a new exoskeleton and harden it after a molt. Without enough, molts go wrong. Keep cuttlebone and crushed oyster shell in the tank at all times so crabs can graze when they need it. Many crabs also eat their own shed exoskeleton to recover calcium, and some will nibble shell fragments.

Feeding schedule

Offer small amounts and watch what vanishes. Over a couple of weeks you will learn each crab's favorites. Rotate foods so no one gets bored, and reduce portions if the tank is full of leftovers each morning.

Shells, Molting & Growth

A hermit crab's body is soft, and the shell is its portable home, armor, and moisture reservoir all at once. The shell holds a little water around the crab's gills, which is part of how it stays moist even when the air dries. A crab without a good shell is a crab in danger. Because the crab grows, it must keep changing shells, and that is why spare shells are not a bonus but a necessity.

Shell sizes and swaps

A good shell is natural, unpainted, and clean, with an opening that is slightly larger than the crab's current shell opening. The crab should be able to pull itself completely inside and seal the opening with its large claw. A shell that is much too big is heavy and awkward; one that is too small leaves the crab exposed.

Before adding a new shell, rinse it, soak it in dechlorinated water, and let it dry. Use only plain water; no soap or bleach.

How to tell it is time for a bigger shell

Crabs grow after each molt, so a shell that fit last year may be too small now. Watch for a crab that seems cramped, a large claw that no longer seals the opening, or a crab hanging around the shell pile and trying shells on. Offer several new shells, one or two sizes up, and let the crab choose. A crab inspecting shells at night is perfectly normal.

The molt cycle, step by step

1. Preparation. The crab eats and drinks more, becomes dull in color, and its eyes may look cloudy. It may be lethargic or restless and often begins to dig.
2. Burial. The crab digs a tunnel or chamber and seals itself underground, often for weeks. Larger crabs may stay under for two to three months or more.
3. The shed. Underground, the old exoskeleton splits and the crab backs out of it, soft and vulnerable.
4. Hardening. The new skin takes time to firm up, and the crab absorbs calcium and rests, still out of sight.
5. Emergence. The crab surfaces, often hungry, usually eats its old exoskeleton for calcium, drinks, and may change shells.

Young crabs molt several times a year; large adults may molt only once every year or two. A crab with a stalled shed, or a crab that emerges too early, is at risk.

What not to do

• Do not dig up a buried crab. Even if it has been gone for months.
• Do not shine lights, tap the glass, or poke into the sand near a suspected burial.
• Do not let the humidity drop or the tank dry out during a molt.
• Do not move a molting crab unless absolutely necessary; ask us first.
• Do not remove the old exoskeleton right away; leave it for the crab to eat.
• Do not mistake a discarded exoskeleton for a dead crab. It looks like a pale, empty ghost of the crab and is not a problem.

Shell fights and shell stress

Crabs sometimes try to evict a neighbor from a better shell. This is normal behavior, but it can turn nasty if shells are scarce. Plenty of spare shells in several sizes is the best fight prevention. A crab that has been pulled from its shell or that has dropped out of a shell on its own needs a suitable replacement within minutes.

Common Challenges & Solutions

Low humidity and suffocation

What you see: a crab that sits on the surface, sluggish, slow to retreat into its shell, with bubbling or froth around the mouth, or crabs that dig in and refuse to come out. The hygrometer reads below 65%. Why: a land hermit crab's modified gills must stay moist to absorb oxygen. When the air is too dry, the gills dry out, and the crab slowly suffocates. It is the most common cause of early death in pet crabs. What to do: check the hygrometer right away, close gaps in the lid, dampen the substrate with dechlorinated water, mist the walls, and make sure both pools are full. Raise humidity gradually to 70–80% instead of drenching the crabs. When to ask for help: if a crab is limp, unresponsive, or has been struggling for hours after you have fixed the humidity, contact us the same day.

Stuck or failed molts

What you see: a crab that surfaces with the old exoskeleton partly stuck, a crab that emerges soft and weak, or a crab that dies partway through. Why: low humidity, shallow substrate, poor calcium, stress, or a disturbed burrow can all interrupt a molt. What to do: raise humidity into range, keep the tank quiet, make sure substrate is deep and damp, and keep calcium available. Do not pull on the stuck skin. When to ask for help: if a crab is trapped in its exoskeleton on the surface or looks to be struggling, call us immediately.

Shell fights and shell stress

What you see: crabs pinching and tugging at each other's shells, a crab out of its shell and wandering exposed, a crab constantly switching shells without settling, or a crab with a shell that is clearly too small. Why: the wrong shells, too few shells, or too small a tank leads to competition. Naked crabs are vulnerable, and cramped or heavy shells cause stress. What to do: add more spare shells in a range of sizes with proper opening shapes, place them in several spots, and make sure the tank is large enough. If a crab is out of its shell, leave several options nearby and keep other crabs away briefly. When to ask for help: if a crab has been out of its shell for more than a few hours and is not molting, or if injuries are visible.

Heat or cold stress

What you see: crabs that are listless, inactive, and refuse to eat in the cold; crabs that stay on the surface, dry, and sluggish, or that look weak in the heat. Why: the thermostat has failed, the room has changed temperature, or the heater is badly placed. Cold below about 70°F slows crabs; heat above about 85°F dries them and stresses their gills. What to do: check thermometers at both ends of the tank, fix the heater or thermostat, and adjust slowly. Move the tank away from drafts or sun. When to ask for help: if the tank has been outside range for a day or more and any crab looks unwell.

Poisoning by copper, cleaners, or paint

What you see: sudden lethargy, a crab dropping out of its shell, odd twitching, crabs refusing food, or several crabs failing at once. Why: crabs are crustaceans and are very sensitive to copper, chlorine, chloramine, aerosols, air fresheners, bleach, paint, and varnish. Painted shells can chip and be eaten, and copper hides in some foods, supplements, and metal dishes. What to do: move the tank to fresh air if fumes are the problem, rinse any surfaces that may have been cleaned with chemicals, replace the water, remove painted shells and suspect foods, and replace metal dishes with glass or ceramic. When to ask for help: any suspected poisoning is urgent; call us right away.

Mites and pests

What you see: tiny moving specks on the crabs' shells and legs, or clusters in the corners of the tank, often after a fruit or bark addition. Why: many tiny mites ride in with food, wood, or substrate and thrive in damp, warm tanks. Some are harmless scavengers; heavy infestations are stressful. What to do: reduce food waste, clean pools more often, remove uneaten food promptly, and avoid adding unsanitized wood or leaves. Do not use sprays or pesticides near the tank. When to ask for help: if crabs look weak, are covered in mites, or if you are not sure what you are seeing, send us a photo or call.

Missing limbs

What you see: a crab missing a claw, leg, or antenna. Why: crabs drop limbs (a process called autotomy) when pinched, frightened, or injured. It is a defense, not a disease. What to do: keep the tank calm, humidity correct, and food and calcium available. The limb typically regrows over one or more molts, though it may come back smaller at first. When to ask for help: if the stump is bleeding, discolored, or looks infected.

Stress after transport

What you see: a new crab that stays buried, refuses food, or sits motionless. Why: many crabs are shipped, handled, and held in poor conditions before arriving. They may be dehydrated, underfed, and stressed. What to do: set up the tank in advance, add the crabs gently, give them quiet, darkness, humidity, and food and water, then wait. Do not dig them up. When to ask for help: if there is a strong decay smell, or a crab does not recover after a couple of weeks.

Water contamination and pool accidents

What you see: cloudy or smelly pool water, slimy dishes, or a crab stuck in a pool. Why: food and droppings foul small pools quickly; chlorinated tap water irritates gills; pools that are too deep or have no ramps can trap a small crab. What to do: change both pools daily or every few days, scrub them weekly, use only dechlorinated fresh water and properly mixed marine salt water, and check ramps. Lift out and rest any crab found struggling. When to ask for help: if a crab seems weak after being stuck in water.

Mold, gnats, and fruit flies

What you see: fuzzy growth on food, a sour smell from the substrate, or clouds of small flies. Why: high humidity and leftover fresh food invite mold and insects. What to do: remove uneaten food within a day, spot-clean daily, let the surface breathe a little, and replace any moldy substrate or décor. When to ask for help: if the smell persists or mold spreads across the substrate.

Quick reference

Handling

Gentle handling, not cuddling

Hermit crabs are wonderful to watch and can become used to a calm hand, but they are not cuddly pets. Handling is stressful for them, and a stressed crab can pinch or drop a limb. Keep sessions short, a few minutes at a time, and handle only when you have a reason: checking on a crab, moving it, or letting it explore.

How to pick up a hermit crab

Approach slowly from the side, never from above. Place your fingers on the back of the shell, away from the opening, and lift with a gentle scoop, supporting the shell from below with your other hand. Hold the crab low over a soft surface or the sand, so a drop does not hurt. A crab will often retreat into its shell and then slowly come out and walk across your palm once it relaxes.

Preventing pinches

A pinch from a hermit crab is a surprise and sometimes a painful one. Crabs pinch when frightened, when they feel unsupported, or when they are pulled. Never pull on a crab that has pinched you. It will grip harder, and it may drop a claw or leg. Instead, stay still, place it gently on the sand or a firm surface, and let it release on its own. You can also lower it into a shallow dish of lukewarm dechlorinated water; many crabs let go. Never shake your hand, and never try to pry a claw open.

Hygiene

Wash your hands with plain, unscented soap before and after touching the crabs or the tank, and rinse very well. Lotions, perfumes, hand sanitizer, and soap residue can harm a crab. As with any animal, wash after contact, do not eat or drink near the tank, and keep the crab dishes and tank tools away from the kitchen.

Children

Children love hermit crabs, and with supervision they can be wonderful first-time caretakers. Teach them to sit on the floor to hold a crab, keep their hands low and cupped, stay quiet and still, and never squeeze or turn the crab upside down. Remind them that crabs are shy, that it is fine if the crab prefers to hide, and that the crab is not a toy. Adults should handle all water changes, tank adjustments, and any troubleshooting.

Routine Care Calendar

When to Ask for Help

Hermit crabs hide illness well, and they are small enough that trouble can turn serious in a day. When you are unsure, ask. Veterinarians who treat crustaceans are rare, but some exotic-animal vets will advise on husbandry or evaluate a sick crab, and the Association of Reptile and Amphibian Veterinarians keeps a directory that can point you toward an exotic-animal practice near you. Call ahead and ask whether they will see invertebrates. For everyday questions about humidity, shells, food, or setup, call us at (717) 983-8069. We would rather talk it through.

Act today:

• A crab out of its shell, limp or unresponsive, and not a clear molt
• A crab stuck partway out of an old exoskeleton on the surface
• Froth or bubbles at the mouth, or a crab that is gasping or very sluggish in dry air
• Humidity below 60% for several hours, or temperature below 65°F or above 85°F
• Any suspected chemical exposure: fumes, aerosols, paint, cleaning products, copper
• A crab trapped or struggling in a water dish
• A strong, rotten smell coming from the tank
• Several crabs becoming weak at the same time
• Bleeding, oozing, or white fuzzy growth on a crab

Book within a few days:

• A crab that has refused food for more than a week without signs of molting
• A crab constantly switching shells and never settling
• Heavy mites or insects on the crabs
• A missing limb that looks discolored, or that shows no regrowth after two molts
• Repeated shell fights, injuries, or a crab that is being bullied
• A buried crab whose absence is unusually long, with no smell and no sign of trouble (ask us for guidance; never dig)

FAQ

How long do hermit crabs live?

With excellent care, land hermit crabs commonly live 10 to 15 years or more, and some live far longer, which makes them much longer-term pets than most people expect. The painful flip side is that many pet crabs die within weeks or months, almost always because of housing problems such as dry air, small plastic cages, painted shells, and the wrong substrate. The factors that most reliably extend life are steady humidity of 70 to 80 percent, a deep damp sand and coconut fiber floor for burrowing and molting, temperatures of 75 to 80°F, two clean water pools, a varied diet, plenty of spare shells, and company from other crabs.

What do hermit crabs eat?

Hermit crabs are omnivorous scavengers that need variety, not a single food. Build the menu around quality hermit crab pellets that are free of copper sulfate, preservatives, and ethoxyquin, then add fresh vegetables and fruit such as carrot, leafy greens, mango, berries, and coconut. Offer a small protein bite such as plain cooked shrimp or egg once or twice a week, along with occasional unsalted nuts and seeds. Keep calcium available at all times through cuttlebone and crushed oyster shell. Avoid onion, garlic, anything with preservatives (including sulfites in dried fruit), copper-containing foods, salty or sugary processed food, large amounts of citrus, and produce with pesticide residue.

What humidity do hermit crabs need?

Keep the tank at 70 to 80 percent humidity, measured with a digital hygrometer at crab level (the dial gauges in kits are unreliable). Land hermit crabs breathe with modified gills that must stay damp to work, so low humidity does not just make them uncomfortable, it slowly suffocates them. You get there with a tight-fitting lid, damp sandcastle-consistency substrate, two open water pools, and light misting with dechlorinated water. If the reading drops below 65 percent, treat it as a problem to fix that day.

What size tank do hermit crabs need?

A 20-gallon glass aquarium is the minimum for two or three small crabs, and a 40-gallon breeder tank is the better choice for larger groups or bigger crabs. Glass with a tight lid holds heat and humidity far better than mesh or plastic, and the tank needs room for six inches of substrate, two water pools, climbing branches, hides, and a shell collection. Skip the small plastic crab cages and kits with painted décor; they are the most common reason crabs do not survive. When in doubt, go larger, and plan to upgrade as the group grows.

Do hermit crabs need salt water?

Yes, they need access to both fresh and salt water, in two separate shallow pools. Fresh water must be dechlorinated, because chlorine and chloramine in tap water irritate their gills. The salt pool should be made with a marine salt mix designed for saltwater aquariums, mixed to the package directions with dechlorinated water. Never use table salt, which can contain iodine and anti-caking agents, and avoid mixes with added copper. Both pools should be shallow with a ramp, stones, or a sponge so every crab can climb out safely, and both should be changed daily or every few days.

Why is my hermit crab buried?

Most of the time, it is molting, which is when a crab sheds its old exoskeleton and grows a new, larger one in the safety of a burrow. Signs that a molt is coming include lethargy, dull color, cloudy eyes, eating and drinking more, and digging. A buried crab can stay under for weeks, and large crabs for two to three months or more. Newly arrived crabs also bury themselves to recover from stress. Do not dig the crab up. Keep the humidity up, keep the tank quiet, and wait. The only reason to disturb the sand is a strong, persistent smell of decay at a specific spot.

How many hermit crabs should I get?

Plan on at least two or three, and ideally a few more if your tank can comfortably handle them. Hermit crabs are social animals that eat, explore, and interact in groups, and a single crab often becomes withdrawn. More crabs also need more room, more shells, more hides, and more food stations, so scale the tank to the group: 20 gallons for two or three small crabs, and 40 gallons or more for a larger group. Keep a generous shell collection on hand so a growing group does not turn into a shell contest.

Do hermit crabs need heat?

Yes. They come from warm coastlines and need the tank at 72 to 80°F, with an ideal range of about 75 to 80°F and a gradient so they can choose. Heat the tank with an under-tank or tank-wall heater on a thermostat, and avoid heat lamps, which dry out the air that their gills depend on. Check temperatures with digital thermometers every day, and never let the tank drop below about 70°F. Cold crabs go inactive, stop eating, and become vulnerable to illness.

Do hermit crabs bite?

Technically, hermit crabs pinch rather than bite, using their claws, and they do it when they are frightened, handled roughly, or unsupported. A pinch can hurt but is rarely dangerous. If a crab grabs you, stay calm, do not pull, and gently place it on a firm surface or in a shallow dish of lukewarm dechlorinated water so it will release. Pulling can cause the crab to drop its claw or leg. Pick up crabs gently from the side and back of the shell, handle them low over a soft surface, and keep sessions short.

Is my hermit crab dead or molting?

Look at the whole picture before you decide. A molting crab is usually buried or hidden, may have been dull and sluggish beforehand, and gives off no strong smell. A crab that is dead typically hangs limp and unresponsive out of its shell, does not react when you gently touch the shell, and smells strongly of rot. A pale, empty-looking crab shape lying in the tank is probably a shed exoskeleton, which crabs often eat for calcium, and is not a dead crab. If you are not certain, assume it is molting, leave it alone, and keep humidity high. If a strong decay smell persists for a couple of days, call us.

Ready to shop? Start with Hermit Crabs. 10% of every purchase supports no-kill animal shelters.

Every Purchase Gives Back

Before we earn a dime, 10% of every purchase at Walnut Creek Supply goes to no-kill animal shelters across the country. Not at checkout. Not as an option. Off the top of every order, every day, because we believe responsible pet ownership and community care are the same commitment made in two directions.

For hermit crab keepers, that matters in a specific way. Hermit crabs are often bought on impulse, and far too many are sold without the tank, the humidity, or the shells that would let them live for a decade. By reading this guide you have already done the thing most buyers do not: you looked before you leapt. That makes you exactly the kind of keeper these animals need.

We are a family business in Christiana, Lancaster County, Pennsylvania. We grow our own food, keep our own animals, and stock the clean-label, USA-sourced goods we would put in front of our own pets. No mystery ingredients, no painted shells, no paint-and-plastic crab cages, just honest advice and honest products. If you have a question about your humidity, your shell collection, your salt pool, or a crab who has been buried for longer than you would like, call us at (717) 983-8069. We are glad to help.

Welcome to a decade or more with one of the most charming little neighbors you will ever keep.

_From our family to yours,_ Walnut Creek Supply — Christiana, Lancaster County, Pennsylvania _walnutcreeksupply.com_

How long do hermit crabs live?

With excellent care, land hermit crabs commonly live 10 to 15 years or more, and some live far longer, which makes them much longer-term pets than most people expect. The painful flip side is that many pet crabs die within weeks or months, almost always because of housing problems such as dry air, small plastic cages, painted shells, and the wrong substrate. The factors that most reliably extend life are steady humidity of 70 to 80 percent, a deep damp sand and coconut fiber floor for burrowing and molting, temperatures of 75 to 80°F, two clean water pools, a varied diet, plenty of spare shells, and company from other crabs.

What do hermit crabs eat?

Hermit crabs are omnivorous scavengers that need variety, not a single food. Build the menu around quality hermit crab pellets that are free of copper sulfate, preservatives, and ethoxyquin, then add fresh vegetables and fruit such as carrot, leafy greens, mango, berries, and coconut. Offer a small protein bite such as plain cooked shrimp or egg once or twice a week, along with occasional unsalted nuts and seeds. Keep calcium available at all times through cuttlebone and crushed oyster shell. Avoid onion, garlic, anything with preservatives (including sulfites in dried fruit), copper-containing foods, salty or sugary processed food, large amounts of citrus, and produce with pesticide residue.

What humidity do hermit crabs need?

Keep the tank at 70 to 80 percent humidity, measured with a digital hygrometer at crab level (the dial gauges in kits are unreliable). Land hermit crabs breathe with modified gills that must stay damp to work, so low humidity does not just make them uncomfortable, it slowly suffocates them. You get there with a tight-fitting lid, damp sandcastle-consistency substrate, two open water pools, and light misting with dechlorinated water. If the reading drops below 65 percent, treat it as a problem to fix that day.

What size tank do hermit crabs need?

A 20-gallon glass aquarium is the minimum for two or three small crabs, and a 40-gallon breeder tank is the better choice for larger groups or bigger crabs. Glass with a tight lid holds heat and humidity far better than mesh or plastic, and the tank needs room for six inches of substrate, two water pools, climbing branches, hides, and a shell collection. Skip the small plastic crab cages and kits with painted décor; they are the most common reason crabs do not survive. When in doubt, go larger, and plan to upgrade as the group grows.

Do hermit crabs need salt water?

Yes, they need access to both fresh and salt water, in two separate shallow pools. Fresh water must be dechlorinated, because chlorine and chloramine in tap water irritate their gills. The salt pool should be made with a marine salt mix designed for saltwater aquariums, mixed to the package directions with dechlorinated water. Never use table salt, which can contain iodine and anti-caking agents, and avoid mixes with added copper. Both pools should be shallow with a ramp, stones, or a sponge so every crab can climb out safely, and both should be changed daily or every few days.

Why is my hermit crab buried?

Most of the time, it is molting, which is when a crab sheds its old exoskeleton and grows a new, larger one in the safety of a burrow. Signs that a molt is coming include lethargy, dull color, cloudy eyes, eating and drinking more, and digging. A buried crab can stay under for weeks, and large crabs for two to three months or more. Newly arrived crabs also bury themselves to recover from stress. Do not dig the crab up. Keep the humidity up, keep the tank quiet, and wait. The only reason to disturb the sand is a strong, persistent smell of decay at a specific spot.

How many hermit crabs should I get?

Plan on at least two or three, and ideally a few more if your tank can comfortably handle them. Hermit crabs are social animals that eat, explore, and interact in groups, and a single crab often becomes withdrawn. More crabs also need more room, more shells, more hides, and more food stations, so scale the tank to the group: 20 gallons for two or three small crabs, and 40 gallons or more for a larger group. Keep a generous shell collection on hand so a growing group does not turn into a shell contest.

Do hermit crabs need heat?

Yes. They come from warm coastlines and need the tank at 72 to 80°F, with an ideal range of about 75 to 80°F and a gradient so they can choose. Heat the tank with an under-tank or tank-wall heater on a thermostat, and avoid heat lamps, which dry out the air that their gills depend on. Check temperatures with digital thermometers every day, and never let the tank drop below about 70°F. Cold crabs go inactive, stop eating, and become vulnerable to illness.

Do hermit crabs bite?

Technically, hermit crabs pinch rather than bite, using their claws, and they do it when they are frightened, handled roughly, or unsupported. A pinch can hurt but is rarely dangerous. If a crab grabs you, stay calm, do not pull, and gently place it on a firm surface or in a shallow dish of lukewarm dechlorinated water so it will release. Pulling can cause the crab to drop its claw or leg. Pick up crabs gently from the side and back of the shell, handle them low over a soft surface, and keep sessions short.

Is my hermit crab dead or molting?

Look at the whole picture before you decide. A molting crab is usually buried or hidden, may have been dull and sluggish beforehand, and gives off no strong smell. A crab that is dead typically hangs limp and unresponsive out of its shell, does not react when you gently touch the shell, and smells strongly of rot. A pale, empty-looking crab shape lying in the tank is probably a shed exoskeleton, which crabs often eat for calcium, and is not a dead crab. If you are not certain, assume it is molting, leave it alone, and keep humidity high. If a strong decay smell persists for a couple of days, call us.