How to Care for a Marine Hermit Crab

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Things You'll Need

  • Tank

  • Saltwater

  • Shells

  • Saltwater test kit

  • Hydrometer

  • Thermometer

  • Food


Wash your hands with only water before handling your marine hermit crab. Do not use soap, as the residue left in the tank water can poison the crabs.

Always unplug any electrical equipment that is in your marine hermit crab’s tank before placing your hands inside. Not doing so can cause electric shock.


Healthy water contains no ammonia or nitrates and should have a specific gravity level of 1.022 to 1.0240, according to In addition, the salinity should register between 30 to 40 parts per trillion, the pH should be 8.2 and the temperature should be somewhere between 72 and 78 degrees Fahrenheit.

Marine hermit crabs live under the water and typically make good pets. According to the hermit crab information website, marine hermit crabs are the most intelligent, active and smell-perceptive hermit crabs out of the more than 800 different hermit crabs species that exist. Because of their strong exoskeletons, marine hermit crabs can sustain poor qualities of water, making them very forgiving to the mistakes many first-time marine hermit crab owners can make. However, in order to keep your marine crab healthy and around for a while, follow a few simple techniques.


Step 1

Keep your marine hermit crab submerged in either synthetic or natural salt water at all times, states Marine hermit crabs have gills that can only breathe under water; however, it is still possible to handle your hermit crab, if carefully done under water. Keep your water chlorine-free and use natural marine saltwater, states Using saltwater that doesn't contain natural salt may include iodized salt, which contains chlorine.

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Step 2

Supply your marine hermit crab with many shells. Marine hermit crabs like to switch their shells often. Some will even trade in their old shells for new ones daily. Marine hermit crabs need shells that will fit comfortably with their eye stalks. Choose shells similar to what your marine hermit crab was originally wearing when you obtained it.


Step 3

Maintain a healthy nitrogen system in your tank. Regularly test the quality of your marine hermit crab's water with a saltwater test kit, hydrometer and thermometer, suggests

Step 4

Feed your marine hermit crab a proper, healthy diet. Small hermit crabs—those the size of peas or smaller—can typically survive on plants, algae, uneaten fish food and fish waste, according to Larger crabs require more substance in their diet, such as hermit crab pellets, chicken, turkey, lettuce and earthworms. Either hand-feed your crab underwater with 12-inch tweezers, or remove the crab from its tank and place it into a container that is filled with saltwater and give it food in there. It is not advisable to pour food into the tank, as this method does not ensure that each crab is well-fed and it creates large amounts of food debris, which can alter the quality of the tank water.