Hermit Crab Care Guide: Habitat, Diet & Shell Selection [2026]

Why Hermit Crabs Make Great Pets

Land hermit crabs (Coenobita clypeatus) are curious, social crustaceans that swap shells as they grow, climb everything in sight, and develop distinct personalities. They are quiet, hypoallergenic, and relatively low-cost to keep.

Despite their name, hermit crabs are not solitary — they are highly social and thrive in groups. In the wild, they live in colonies of hundreds.

Tank Setup

Tank Size

• Minimum: 10-gallon glass aquarium for 2-3 small crabs
• Recommended: 20-29 gallon tank for 3-6 crabs
• Rule of thumb: 5 gallons per crab
• Glass aquariums retain humidity much better than wire cages or plastic bins
• A glass or acrylic lid is essential to maintain humidity

Substrate

Substrate depth is critical — hermit crabs bury to molt:

• Mix: 5 parts play sand to 1 part coconut fiber (eco earth)
• Depth: At least 6 inches, or 3 times deeper than your largest crab
• Consistency: Should hold its shape when squeezed (like sandcastle consistency)
• Never use calcium sand, gravel, or wood chips

Temperature and Humidity

• Use an under-tank heater (UTH) on the back wall of the tank (not under the bottom — crabs dig)
• Monitor with a digital thermometer/hygrometer
• Mist with dechlorinated water if humidity drops
• Temperatures below 65°F can be lethal
• Humidity below 70% damages their modified gills and suffocates them

Water Pools

Hermit crabs need two water dishes at all times:

• Freshwater pool — treated with a water conditioner to remove chlorine/chloramine
• Saltwater pool — made with marine salt mix (Instant Ocean or similar), never table salt
• Both pools must be deep enough for crabs to submerge but have a safe way to climb out (ramp, sponge, or rocks)

Decorations

• Climbing structures: Driftwood, cholla wood, coconut huts, cargo nets — hermit crabs are avid climbers
• Hides: Coconut half-shells, cork bark, and caves
• Extra shells: Always provide 3-5 extra shells per crab in various sizes and shapes (turbo shells preferred)
• Avoid painted shells — the paint is toxic

Diet

Hermit crabs are omnivorous scavengers with a diverse diet.

Safe Foods

• Proteins: Dried shrimp, krill, bloodworms, boiled egg, unseasoned cooked chicken
• Fruits: Mango, coconut, apple, banana, grapes (no citrus)
• Vegetables: Spinach, kale, carrots, sweet potato, zucchini
• Other: Cuttlebone (calcium), crushed oyster shell, plain popcorn (air-popped, no salt/butter)
• Leaf litter: Oak, magnolia, and sea grape leaves — natural foraging material

Foods to Avoid

• Anything with pesticides, table salt, garlic, onion, or citrus
• Processed foods, bread, dairy
• Metal food dishes (use glass, ceramic, or coconut shells)

Feeding Tips

• Offer small portions daily and remove uneaten food after 24 hours
• Hermit crabs eat very little — do not overfeed
• Rotate foods to provide nutritional variety
• They are nocturnal feeders — place food in the evening

Molting

Molting is the most critical and dangerous period in a hermit crab's life.

Signs of Pre-Molt

• Lethargy, decreased activity
• Digging down into substrate
• Eating and drinking excessively (storing water and nutrients)
• Dull, ashy-looking exoskeleton
• Gel limb (a translucent limb bud forming where a limb was lost)

During Molting

• The crab buries underground for 2 to 8 weeks (larger crabs take longer)
• NEVER dig up a molting crab — this is the number one cause of death
• The crab sheds its exoskeleton and eats it to recycle calcium and minerals
• Leave the crab completely undisturbed until it resurfaces

After Molting

• The new exoskeleton is soft and vulnerable for several days
• The crab may change shells during this time
• Offer extra calcium-rich foods (cuttlebone, crushed eggshell)

Shell Selection

Shells are a hermit crab's most prized possession:

• Provide 3-5 extra shells per crab in graduated sizes
• Turbo shells (turbo, Mexican turbo) are the most popular with hermit crabs
• Natural shells only — never painted, lacquered, or decorated shells
• Boil new shells for 5 minutes and let cool before offering
• If a crab is naked (shell-less), it is an emergency — isolate in a dark container with damp substrate and appropriate-sized shells

Common Health Issues

Surface Molting

A crab molting on the surface (not buried) is in danger. Gently isolate it in a separate container with moist substrate and cover it with a coconut half-shell for darkness and protection.

Mites

Tiny dots moving on the crab or in the tank. Often caused by overfeeding or poor substrate conditions. Clean the tank, replace substrate, and bathe crabs in dechlorinated saltwater.

Shell Fights

Crabs may attack each other for shells. This is almost always caused by insufficient shell choices. Add more spare shells immediately.

Lost Limbs

Hermit crabs can lose legs or claws from stress, fighting, or mishandling. They regenerate lost limbs during subsequent molts. Ensure the crab has a calm environment, good nutrition, and proper humidity.

Conclusion

Hermit crabs are social, fascinating pets that require specific but achievable conditions: warm temperature (75-85°F), high humidity (70-80%), deep substrate for molting, both fresh and saltwater pools, a varied omnivore diet, and plenty of spare shells. Get these basics right, keep them in groups, and hermit crabs can live well over a decade as entertaining and low-maintenance companions.