Why Won’t My Hermit Crab Eat? (9 Causes & Easy Fixes)

Hermit crabs stop eating because of stress, molting, wrong temperature, low humidity, new environment, boring food, no salt water, loneliness, or illness. The good news? In most cases, the fix is simple and your crab will start eating again once you find and solve the problem. Hermit crabs do not starve themselves on purpose. If they are not eating, something in their environment needs to change. Here are the 9 most common causes and exactly what to do about each one.

1. It Is Molting (The Most Common Reason)

If your hermit crab has buried itself and stopped eating, it is very likely molting. During a molt, crabs dig underground, shed their entire outer skin, and grow a new one. This process takes 2 weeks to 3 months depending on the crab’s size. They do not eat regular food during this time – instead, they eat their own shed skin, which gives them the calcium and nutrients they need. Do not dig them up. Leave the crab completely alone and keep offering food in the dish for your other crabs as normal. Your molting crab will come back up and start eating when it is ready.

Bonus: What Do Hermit Crabs Like

2. It Is New and Still Adjusting

A hermit crab that just arrived from a pet store is extremely stressed. It has been taken from the wild, shipped in poor conditions, kept in a dry tank, and then moved again to your home. This is called post-purchase stress (PPS) and almost every new hermit crab goes through it. The crab may hide, refuse food, and stay buried for days or even weeks. This is normal. Keep offering fresh food every evening, make sure conditions are right, and give the crab time. It will start eating once it feels safe enough.

3. The Tank Is Too Cold

Hermit crabs are cold-blooded. When the tank drops below 72°F, their body slows down – digestion stops, they become sluggish, and they lose interest in food. Check your thermometer. The tank should be between 75°F and 85°F, with the sweet spot around 78°F to 82°F. If it is too cold, adjust your heat mat or add a thermostat. You should see your crab perk up and start eating again within a day or two once the temperature is right.

4. The Humidity Is Too Low

Hermit crabs smell their food through moist air. When humidity drops below 70%, their sense of smell weakens and they literally cannot find their food. Low humidity also damages their gills, making them feel unwell and lose interest in eating. Check your hygrometer. Humidity should be between 70% and 80%. If it is too low, seal the lid, mist the tank, add a moss pit, or check if the substrate is damp enough.

5. They Are Bored of the Same Food

Research shows that hermit crabs prefer a different food every time they eat. If you have been feeding the same pellets or the same fruit every night, your crab may simply be bored and waiting for something new. Switch it up. Try coconut one night, dried shrimp the next, then sweet potato, then mango. Rotate between protein, fruit, vegetables, and calcium. Many owners find that their “picky eater” was just a crab waiting for a menu change.

6. No Salt Water Access

This is one that most people miss. Hermit crabs need salt water to regulate their body chemistry and boost their sense of smell. Without a salt water pool, they cannot smell food as well and may stop looking for it. Make sure your tank has two water dishes – one fresh, one salt – both deep enough to submerge in. Use marine-grade aquarium salt only, never table salt.

7. Something Is Stressing Them Out

Stressed hermit crabs lose their appetite fast. Common stress triggers include:

• Loud noises or vibrations near the tank (TV, music, foot traffic).
• Bright lights at night that disrupt their natural schedule.
• Being handled too often. A little is fine, but too much causes stress.
• A recent tank change – new substrate, rearranged decorations, or moving the tank to a different room.
• Overcrowding – too many crabs in a tank that is too small.
• Shell fights – not enough spare shells leads to aggression and stress.

Fix the stress source and your crab should return to eating within a few days. Keep the tank in a calm, quiet spot with a steady routine.

Bonus: How to Feed Hermit Crabs

8. It Is Alone

A single hermit crab kept without companions often becomes inactive and stops eating. In the wild, they live in groups of dozens to hundreds. A lone crab can feel unsafe and stressed without other crabs around. If you only have one crab, adding 2 more companions is one of the fastest ways to get it eating and moving again. Many owners report their single crab “came alive” within days of adding tank mates.

9. It May Be Sick

This is the least common reason, but it is worth checking if nothing else works. A sick hermit crab may stop eating, become very still, or give off a fishy or rotten smell. Leg dropping is usually a sign of stress rather than illness, so check the stress triggers in section 7 first. If the crab smells bad, it may have already passed away. If it is still moving but not eating after you have fixed all the conditions above, give it time. Hermit crabs are tougher than they look and often recover on their own when their environment is right.

Wait – It Might Actually Be Eating

Before you panic, check this first: hermit crabs eat very small amounts. A single crab eats about a pea-sized portion per night. The food might look untouched, but if you look closely, you may see tiny bite marks or small pieces missing. Hermit crabs also eat things in the tank you did not put there – moss, leaf litter, algae on decorations, bits of wood, and even their tank mates’ shed exoskeletons. So, your crab may actually be eating just fine – you are just not seeing it. Try putting a very small amount of something smelly (like a tiny piece of dried shrimp) in the dish and check for bite marks in the morning.

Conclusion:

If your hermit crab is not eating, check the 9 causes in order: molting, new crab stress, cold tank, low humidity, boring food, no salt water, general stress, loneliness, and illness. In most cases, fixing the environment is all it takes. Remember that hermit crabs eat tiny amounts at night – so your crab might actually be eating more than you think. Stay patient, keep conditions steady, and offer something new every evening. Your crab will come around.

Bonus: What Can Hermit Crabs NOT Eat? 

Frequently Asked Questions