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why is my hermit crab white?

Why Does My Hermit Crab Look White?

Healthy hermit crab colors should be bright and vibrant. Their exoskeletons are white, but they’re covered in fresh skin, giving them a colorful look. If they turn pale or white, a health or environmental issue is likely to blame.

Hermit crabs look white when they’re molting. This is where they shed their exoskeleton, producing a larger one to accommodate its growth. Hermit crab shells also naturally turn white through exposure to salt and calcium bicarbonate. Unfortunately, if your hermit crab is white and not moving, it’s likely to be dead.

Watch out for white mold or mites, as they can create the illusion that your hermit crab’s turning white. Keeping your hermit crab’s environment clean and sanitary should enable you to avoid these issues.

Why Is My Hermit Crab White?

As discussed, hermit crabs should be deep and vibrant in color. However, there’s no universal color you need to look out for, as each species has a different marking. As a result, the paler a hermit crab appears, the more likely it is to be unhealthy.

This doesn’t mean your hermit crab’s sick or dying – it may need a few environmental changes to get it back to its normal coloration. In many cases, it’s the hermit crab’s shell that’s turning white instead of its skin. Nevertheless, these are the most common reasons why hermit crabs turn white:

Wear and Tear

Because hermit crabs carry their shells around with them, wear and tear occur after being bumped and scraped along rocks, accessories, and the sides of the tank. Abrasive sand can also wear down the shell’s polish, causing discoloration that often appears white or pale gray.

Calcium Bicarbonate

Owners need to provide their hermit crabs with shells in various shapes and sizes, which they move into when they outgrow their original shells. Before you put them into the water, clean them first by boiling them in salty water. Shells are comprised of calcium bicarbonate, so this process causes the shells to bleach and turn white.

Overexposure to Salt

Hermit crabs are saltwater creatures. However, overexposure to salt acts in a similar way to bleach, turning the shell white. That being said, this is a more common occurrence in the wild when the shells become immersed in the ocean or washed over by waves on the shore for a long time.

Nutritional Deficiencies

Hermit crabs often appear white or washed out when they don’t consume the right nutrients. Specifically, they’ll turn white if they don’t eat enough calcium and magnesium. Cuttlebone and sea biscuits are good sources of calcium, so be sure to incorporate them into your hermit crab’s diet to bring it back to its full, normal coloration. Hermit crabs also need to consume:

A varied, balanced diet will help your hermit crab get all the nutrients it needs and maintain its bright coloring.


Mite won’t necessarily cause your hermit crab to turn white, but some species appear as small white blotches on the eyes, legs, and body. According to the Journal of Experimental Marine Biology and Ecology, around 15 types of mites affect hermit crabs, including:

  • Acarus siro – aka grain mites
  • Demodex folliculorum – aka follicle mites
  • Dermatophagoides – aka dust mites
  • Liponyssoides sanuineus – aka house mouse mites
  • Oribatid – aka soil mites or moss mites
  • Psocoptera – aka booklice, paperlice or barkflies
  • Sarcoptes scabiei hominis – aka itch or scabies mites
  • Tyrophagus putrescentiae – aka mold mites

Mites are more common than you might think. They enter into the tank through fresh food, woods, rocks, or shells. Mites thrive in warmth, darkness, humidity, and places they can hide. Once they get into the tank, they multiply and cause a full-scale infestation, becoming difficult to eradicate.

hermit crab white after molting


Hermit crabs don’t fade in color from the natural aging process like some mammals. Unfortunately, if you find your hermit crab gray, pale, or white and not moving, it’s likely dead. It’s common for hermit crabs to die suddenly and without warning.

Sadly, molting hermit crabs are commonly mistaken for dead hermit crabs, which is where the confusion lies for inexperienced owners. For that reason, don’t assume your crab’s dead – make sure it’s not molting by observing your hermit crab from afar. This is so you don’t accidentally disturb your pet during this vital process. After a few days, dead hermits start to smell, which gives you your answer.

Why Is My Hermit Crab White After Molting?

During the molting stage, your hermit crab will turn white. This is completely normal and isn’t anything to worry about. The Journal of Experimental Marine Biology and Ecology explains how hermit crabs molt several times in the first three years of their lives, increasing in size and mass each time they molt.

During this process, the hermit crab will shed its exoskeleton and produce a larger one to accommodate its growing body. Molting is a deeply private experience for a hermit crab, and during this time, it will barely move. As a result, owners commonly worry that their hermit crab’s dead or dying.

The molting process lasts for several weeks, if not months. You must leave your hermit crab alone during this process, or there could be disastrous consequences. During a molt, hermit crabs:

  • Bury themselves into their substrate
  • Dig more often, as if they’re making a tunnel
  • Limply hang out of their shells
  • Eat and drink more than usual to store fat and water
  • Develop a glassy or glazed expression in their eyes

Once a hermit crab completes its molt and emerges, it will stop being pale or white and return to its original vibrant color. This is how you’ll know that your hermit crab’s back to normal.

What Is the Fuzzy White Stuff on My Hermit Crab?

It may surprise you to know that white mold is a common occurrence in hermit crab tanks. It can also affect their shells, making them appear partially white and pale. Fortunately, mold is a standard feature of any tank and doesn’t cause any significant health issues. That being said, you should manually clean it up whenever you see it in the tank to keep conditions sanitary.

Mold most often comes from old substrate, but it’s also caused by a lack of airflow in the tank. It’s tricky to get the right combination of airflow and humidity, as you must seal the tank tightly to produce enough moisture for your hermit crabs. Food also tends to get moldy if left in the tank for too long.

Once mold appears, you’ll always have mold spores, so keep an eye on the tank and your hermit crab’s shells to ensure it doesn’t overgrow and become too much of a problem. Once you have mold, it’s likely to return frequently.

In most cases, your hermit crab turning white isn’t anything to worry about. Depending on your hermit crab’s behavior, it’s most likely molting. However, always keep an eye on your pet for any sudden changes and make sure the environment’s always clean and sanitary.