Hermit crab care stays simple when you give warm humid air, dechlorinated water, deep sand, steady heat, and a mixed diet.
Hermit crabs do well when their basic needs are met with care and consistency. This guide lays out exact targets, plain steps, and daily habits that keep small groups thriving. You’ll find the setup checklist, heat and humidity ranges, water prep, safe foods, shell tips, and what to do during a molt. If you came here asking how to keep a hermit crab alive, you’ll leave with a plan you can run today.
How To Keep A Hermit Crab Alive: Targets, Gear, And Daily Habits
Use the quick table below as your at-a-glance setup. It keeps the core needs in one place so you can check them off before you bring a crab home.
| Care Area | Target Or Range | Notes |
|---|---|---|
| Tank Size | 10 gal for 1–2; +5 gal per extra crab | Glass tank with tight lid holds heat and humidity. |
| Temperature | Warm side ~80°F; cool side ~70–75°F | Under-tank heater; check both ends daily. |
| Humidity | 70–90% relative humidity | Use a hygrometer; mist with dechlorinated water. |
| Substrate Depth | 3× the height of your largest crab | Moist “sand + coconut fiber” mix that clumps. |
| Water | Two bowls: fresh & marine saltwater | Always dechlorinate; non-metal bowls. |
| Diet | Daily mix of plant and animal foods | Add calcium with cuttlebone or crushed shell. |
| Shells | 3–5 spare shells per crab | Varied sizes and openings; no paint. |
| Lighting | 10–12 hours light cycle | Low-watt bulb for day; dark or red at night. |
| Hiding & Climbing | Cork, branches, tunnels | Boosts activity and reduces stress. |
Tank Setup That Keeps Crabs Breathing And Growing
Pick A Secure Glass Tank
Start with a glass tank that holds heat and moisture with a tight lid. A 10-gallon tank works for two small adults. Add about five gallons of space for each extra crab. Place the tank away from drafts and direct sun so your readings stay steady.
Heat From Below, Not From A Hot Rock
Land hermit crabs are ectotherms and need a warm zone near 80°F and a cooler zone near the low to mid-70s. Stick an under-tank heater on the side or back pane, not under the entire floor, so a deep corner stays warm without baking the whole base. Add two thermometers—one on the warm side and one on the cool side—so you can see your split at a glance.
Hold The Humidity Sweet Spot
Moist gills need moist air. Aim for 70–90% relative humidity. Put a hygrometer halfway up the wall and check it each day. If readings dip, mist with treated water and add a moss patch or cover part of the lid to cut loss. Keep the sand mix damp enough to clump, not drip.
Build A Dig-Safe Substrate
Pour in a deep base that lets a crab bury fully during a molt. Use clean play sand mixed with coconut fiber at about five parts sand to one part fiber. Pack it to “sandcastle” texture so a tunnel holds its shape. Depth should be three times the height of your largest crab. Skip aromatic wood shavings and dusty litters.
Water: Fresh, Salt, And Always Dechlorinated
Keep two bowls at all times: one with fresh water and one with marine-grade saltwater mixed per the label. Use only aquarium salt made for marine fish. Table salt lacks needed trace elements and may add anti-caking agents. Treat tap water with a conditioner that removes chlorine and chloramine. Many cities use chloramine, which lingers longer than chlorine and harms aquatic life; the EPA’s research on chloramines explains why conditioners must neutralize both.
Bowls should be non-metal, easy to climb, and deep enough for a brief dip. Add smooth stones to create steps. Replace water daily so the mix stays clean. Rinse bowls with hot water; skip soap.
Feeding That Builds Strong Shell And Claws
Offer a mix of plants and proteins each evening, with a small refill in the morning for active groups. Rotate leafy greens, seaweed, squash, apples, berries, and whole grains. Add lean seafood or unsalted dried shrimp a few days a week. Keep a calcium source in the tank, like cuttlebone, crushed oyster shell, or a mineral block. Remove leftovers the next day to keep pests away.
Safe And Unsafe Food Shortlist
- Good picks: nori, spinach, kale, carrots, sweet potato, apple, banana, blueberries, plain popcorn, oats, unsalted nuts, boiled egg, krill, shrimp.
- Avoid: onion, garlic, chives, chocolate, caffeine, alcohol, anything salted or seasoned, and any food treated with pesticide.
How to Keep a Hermit Crab Alive During A Molt
Molting is a full reset where the crab sheds its exoskeleton and reforms a new one. It often stays buried for weeks while the new shell hardens. Your job is to give depth, dark, moisture, and peace. Don’t dig it up. Don’t move the tank. Keep the sand packed and damp so tunnels don’t cave. When you see a crab surface after a molt, leave the shed parts in place for a day or two, since many crabs nibble them for minerals.
Signs A Molt Is Coming
- Reduced activity and more time under the sand.
- Dull, ashy look to the exoskeleton.
- Less interest in food, then a sudden dig-down.
Post-Molt Care
When a crab finishes a molt and reappears, keep the tank steady and avoid handling for a few days. Offer calcium-rich bites and fresh water. If another crab pesters the soft-shelled one, block the path with a cork piece or add a second food dish on the far side to spread traffic.
Shell Swaps Without Drama
Keep three to five spare shells per crab, with a range of sizes and openings. Natural, unpainted shells are the safe choice. Rinse new shells with hot dechlorinated water and let them cool before adding them to the tank. Place them near hides so a shy crab can try them on without pressure.
Social Life, Handling, And Enrichment
Land hermit crabs are social and tend to be more active in small groups. Add climbing branches, vines, and a mix of hides so each crab can pick a spot. If you handle them, hold the shell from behind and keep hands low over the tank.
Close Variation: Keeping A Hermit Crab Alive Long-Term — Settings That Work
Run these checks and you’ll keep readings steady and stress low.
Daily Routine
- Read both thermometers and the hygrometer. Adjust the lid cover or mist to hit the target band.
- Swap fresh and salt water with treated water. Check at night again if the tank runs warm.
- Offer dinner, clear leftovers from yesterday, and wipe dishes.
- Mist the moss patch and turn the light off at night.
Weekly Routine
- Stir the top inch of sand to break any crust while leaving deep zones packed for burrows.
- Boil spare shells, cool, and return. Add one new size if a crab seems cramped.
- Rinse decor in hot water and scrub algae from bowls with a brush.
Deep Clean (Every Few Months)
Plan a deep reset when no crab is buried. Move crabs to a holding bin with their own sand and both water bowls. Bake or replace sand, rinse the tank with hot water, and return packed substrate to full depth.
Troubleshooting: Readings, Behavior, And Health Flags
Low Humidity
Seal more of the lid with plastic wrap or acrylic, add a larger water dish, and mist twice a day. Check that the heater is not drying the tank. Raise the moss area and keep it damp. If the air dips for long stretches, gills dry out and breathing gets hard, so act the same day.
Too Hot Or Too Cool
If the warm side creeps past the low 80s, slide the heater a bit or add a small fan to the room, not into the tank. If the cool side slips under 70°F, add a second small heater on that pane. Watch the substrate temp as well so buried crabs stay safe.
No Interest In Food
Rotate the menu toward fresh plant matter and a mild protein like shrimp. Offer smaller amounts so the dish stays fresh. Check temps and humidity first, then water quality, since off readings are a common cause.
Shell Issues
If two crabs fight, add more hides and more spare shells. Give a range of opening shapes. Painted shells can chip and cause harm, so stick with natural shells.
Second Table: Seven-Day Menu Plan
| Day | Evening Plate | Calcium/Notes |
|---|---|---|
| Mon | Nori, spinach, oats, dried shrimp | Cuttlebone left in tank |
| Tue | Apple slices, carrot shreds, boiled egg | Dust with crushed oyster shell |
| Wed | Sweet potato mash, kale, krill | Swap in a fresh mineral block |
| Thu | Blueberries, quinoa, plain popcorn | Leave shell bits from prior molts |
| Fri | Zucchini, seaweed, tuna flake (unsalted) | Check spare shells and rinse |
| Sat | Pumpkin, pear, unsalted nuts (small) | Top up salt mix with treated water |
| Sun | Spinach, brown rice, shrimp | Full dish wash and dry |
Proof-Backed Targets And Why They Matter
Vet-reviewed care sheets match these ranges: warm end near 80°F with a cooler zone, deep sand mixed with coconut fiber, twin water bowls, and humidity in the 70–90% band. For one vetted overview, read the PetMD hermit crab care sheet. Daily checks beat guesswork, and small tweaks keep stress low once the base is right. Clean bowls and steady heat do the rest.
Bringing It All Together
If you asked how to keep a hermit crab alive, the plan is steady ranges, safe water, deep sand, spare shells, low-light nights, and calm molts. Meet those needs and your crabs can live for years while staying active and curious.