Creating the Perfect Hermit Crab Habitat: A Step-by-Step Guide

Many people mistakenly believe that all hermit crabs live in the ocean. However, land hermit crabs live near the shoreline, which gives them easy access to water when they need it for reproduction or moisture. This is important to consider when building a habitat for your pet crab.

Hermit crabs do not require an elaborate home, but the right temperature and humidity are essential for their health. Land hermit crabs, the most common type of pet crab, come from warm, tropical climates and need a warm, humid environment to survive. Here's a guide to setting up an enclosure that meets their needs.

Picking the Tank

Despite their name, hermit crabs are quite social and do best in groups. To house your hermit crabs comfortably, consider the following:

• Hermit crabs can be housed in either a glass or plastic tank.
• Choose a 10-gallon aquarium with a lid. A sliding glass lid works well to retain humidity.
• Small plastic homes sold as hermit crab kits are usually too small but are excellent for temporary housing or isolation.

The Substrate

Avoid gravel or wood shavings. Good substrate options for a hermit crab tank include:

• Sand: Hermit crabs prefer sand as a substrate because they like to burrow into it. Playground sand, available at home improvement stores, works well and is inexpensive, although aquarium sand is also suitable. Consider rinsing, drying, and baking the sand at 300 F to sterilize it. It can be rewashed and reused. Calcium-based sands are available in various colors but are more expensive.
• Fiber Bedding: Products like coconut fiber-based bedding, such as Forest Bedding made for reptiles, can be used in hermit crab tanks. The finely ground fiber resembles soil and is excellent for burrowing.
• Crushed Coral: Although a good choice, providing an additional area with Forest Bedding or sand is advisable, as hermit crabs may prefer these for molting.

Maintaining Proper Temperature

Hermit crabs thrive at temperatures between 72 and 80 F (22 to 27 C). If the temperature consistently drops below 72 F, the crabs may become weak, stressed, and ill.

• Heater: Unless you live in a tropical climate, you will need to use a heater to maintain optimal temperatures in the crab tank. Under-tank heaters (UTHs), lights, or a combination of both can be used. Different lights can provide heat, so you may need to experiment to find the best combination for your tank.
• Warm and cool sides: Position the UTH under one end of the tank to create a warm side and a cooler side, elevating the temperature a few degrees above room temperature. For ideal temperature control, use a thermostat or timer to maintain temperatures. Ensure a temperature gradient in the tank so the crabs can choose their preferred temperature.
• Adjust the substrate and lighting: Use a reliable thermometer to monitor the temperature near the substrate. If the heater doesn't warm the tank enough, remove some substrate over the heater; thinner substrate increases heat. If the tank is too warm, deepen the substrate. Experiment to achieve stable temperatures.

Lights

Previously, it was believed that hermit crabs were nocturnal and that lights could stress them. However, low-wattage or special night bulbs can be beneficial. Many owners find their crabs are more active and bask near lights when lighting is added to the tank.

• Daytime and nighttime cycles: Provide a light-dark cycle, such as 12 hours of light and 12 hours of dark. Day glow or fluorescent bulbs should be off at night, but special nighttime bulbs can be used if desired.
• Lighting hood: Use a reptile heating/lighting hood over the tank to add lighting. These hoods have two ceramic receptacles for incandescent bulbs, allowing for a day glow bulb on one side and a night glow bulb on the other. Start with 15-watt bulbs, increasing wattage only if necessary, especially in a 10-gallon tank. Wood slats can raise the hood if it overheats the glass. Some hoods have a third receptacle for a fluorescent bulb; owners have reported success with Reptisun 2.0 fluorescent. Reptile heat hoods are best for glass top tanks or screens, though screens complicate humidity regulation and can melt if the lights get too hot.
• Don’t overheat the tank: Avoid desk lamps or high-wattage reptile bulbs, as they may overheat and excessively dry the tank.

Humidity

Adequate humidity, along with the right temperature, is crucial for hermit crabs. They "breathe" through gills, so proper oxygen exchange depends on air humidity. If the air is too dry, crabs can suffocate. Excess humidity causes condensation and promotes bacteria and fungal growth.

• Proper humidity level: Hermit crabs need a relative humidity of around 70–80%. Because this is so important, it is worth investing in a humidity meter, known as a hygrometer, which you can find in the reptile section of the pet store.
• Water dish and sponge: A water dish should suffice for creating proper humidity if the tank is enclosed with solid sides and top. To increase humidity, place a large natural sea sponge in a dish of dechlorinated water. The sponge holds water and has plenty of surface area for evaporation. Keep extra sponges to swap and clean frequently by soaking them in hot dechlorinated water or a sea salt/water mix, then allow to dry completely, as they can harbor bacteria.
• Modify the top of the tank: If a mesh or vented lid is making humidity control difficult, it can be modified by covering most of the top with plastic wrap or clear packing tape.

Cage Furnishings 

A hermit crab's cage needs four essentials: climbing structures, shells, a water bowl, and a food dish.

• Climbing: Land hermit crabs love to climb, and this is a good way to provide some exercise. Choya (or cholla) wood is ideal and can be arranged to allow climbing. Pieces of coral, driftwood, and other types of wood can be used—the reptile section of the pet store is a good place to look for a variety, or check online hermit crab retailers. Artificial plants are also a great addition to the crab tank. Periodically change things around or add different items to provide some variety and interest for the crabs. Some enterprising individuals even use Legos to build climbing structures for their crabs.
• Shells: As hermit crabs grow, they leave behind their shells and take on larger ones that suit them better. But stressful situations could also cause shell evacuation. So, add several clean, empty shells that your crabs will be able to use whenever they wish. You can offer different types of shells of varying sizes to see which ones your hermit crabs prefer, and then offer more of the same types but in larger sizes as they grow. 
• Water: Hermit crabs should have access to both fresh water and salt water, so you will need two water dishes. They should be big and deep enough to let the crabs get into them if they wish to soak—especially the salt water dish—but easy to get out of and not so deep that drowning is a risk. Strawberry hermit crabs should be given a salt pool deep enough to fully submerge themselves, but for most species, it does not need to be that deep. To create steps or ramps that your crab can use to get out of the water, place coral or smooth river stones in any dishes that are deep. Place natural sea sponges in the water dishes so your crabs can use them to drink water (plus, they help with regulating the humidity in the tank). All water given to the hermit crabs or used in the tank should be dechlorinated (the drops available at pet stores). Salt water should be prepared using a marine aquarium salt like Instant Ocean (a mix for saltwater tanks), not the salt made for freshwater tanks, and never table salt.
• Food: Food dishes that are sturdy and shallow, as well as easy to keep clean, are best. You can use flat, plastic dishes that look like rocks (check the reptile section at pet stores). Ceramic dishes that are shallow and designed for small animals can also work well. And you can even use seashells to feed your crabs.