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why is my hermit crab white?

Why Does My Hermit Crab Look White?

The skin of hermit crabs gives them a colorful appearance, even though their exoskeletons are white. If hermit crabs become pale or white, it’s likely due to diet, health, or environmental issues.

Hermit crabs appear white when shedding their exoskeleton to accommodate growth and development.

Their shells whiten naturally through salt and calcium bicarbonate exposure. White mold and mite infestations can also create the impression that a hermit crab is becoming white.

If a hermit crab is white and not moving, it’s likely near death or has already died.

Why Is My Hermit Crab White?

Hermit crabs should be a deep and vibrant color. There’s no universal color because each species has different markings. The paler the hermit crab appears, the more likely it is to be unhealthy.

This doesn’t mean a hermit crab’s sick or dying – it may need specific dietary and environmental changes to restore its natural color. Usually, the hermit crab’s shell turns white, not its skin.

Here are the most common reasons why hermit crabs go white:

Wear and Tear

As hermit crabs carry their shells around, wear and tear occur after being bumped and scraped along rocks, accessories, and the sides of the tank.

Sand can also remove the shell’s luster, turning it white or pale gray.

Calcium Bicarbonate

Owners must 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 in water, they’re cleaned by boiling them in salt water. Shells comprise calcium bicarbonate, so this process can cause the shells to bleach and turn white.

Overexposure to Salt

Hermit crabs are saltwater creatures, but overexposure turns shells white. This is also common 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 get the right nutrients. Specifically, they’ll turn white if they don’t get sufficient carotenoids like beta-carotene and zeaxanthin.

These are red-orange pigments derived from the consumption of certain fruits and vegetables.

hermit crab white after molting


Mites won’t necessarily cause hermit crabs to turn white, but some mite 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 (grain mites).
  • Demodex folliculorum (follicle mites).
  • Dermatophagoides (dust mites).
  • Liponyssoides sanuineus (house mice mites).
  • Oribatid – soil mites or moss mites.
  • Psocoptera (booklice, paperlice or barkflies).
  • Sarcoptes scabiei hominis (itch or scabies mites).
  • Tyrophagus putrescentiae (mold mites).

Mites can enter the tank through food, wood, rocks, and shells.

Mites thrive in warmth, darkness, and humidity, seeking hiding places. Once mites enter the tank, they quickly multiply and cause a full-scale infestation, becoming hard to eradicate.


Unlike human hair, hermit crabs don’t fade in color due to the natural aging process. A once vibrant-colored hermit crab won’t turn ash-gray or white just because it’s getting old.

Unfortunately, if you find a hermit crab that’s gray, pale, or white and not moving, it’s likely dead. It’s common for hermit crabs to die suddenly and without warning.

Molting hermit crabs are commonly mistaken for dead hermit crabs. Don’t assume a hermit crab is always dead because it might still be alive. After a few days, dead hermit crabs start to smell bad.

Why Is My Hermit Crab White After Molting?

During the molting stage, a hermit crab will turn white.

The Journal of Experimental Marine Biology and Ecology explains how hermit crabs molt several times in the first 3 years of their lives, increasing in size and mass each time.

The hermit crab will shed its exoskeleton and produce a larger one to accommodate its growing body. Molting is a private experience for a hermit crab, and it’ll seldom move during this time.

The molting process lasts several months, and it mustn’t be disturbed. During a molt, hermit crabs:

  • Bury themselves into their substrate.
  • Dig more often, as if they’re making a tunnel.
  • Hanging out of their shells limply.
  • Eating and drinking 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’ll stop being white and return to its vibrant color.

What Is the Fuzzy White Stuff on My Hermit Crab?

It may surprise you that white mold is common in hermit crab tanks. White mold can also affect hermit crab shells, making them appear ash-gray or off-color.

Mold originates from decaying food and rotting matter, especially if airflow is lacking. Getting the right level of airflow isn’t easy because you must seal the tank to generate sufficient humidity.

Once mold appears, there will always be mold spores, so monitor the tank and shells to avoid problems. Once there’s mold in the tank, it’s likely to return in the future.

In most cases, a hermit crab turning white is normal. Depending on a hermit crab’s behavior, it’s likely molting its exoskeleton. Always ensure conditions are optimal and the tank is kept clean.