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This is the minimum amount of space you should give your crabs. Always make sure that your tank has a lid to prevent your crabs from escaping and to ensure that it adequately holds humidity. For the best results, use a mesh lid covered with Plexiglas or a screen lid with locks. You can also cover a mesh lid with plastic wrap or weather stripping. Hermit crabs do not need air. Instead they breathe through gills. If your humidity is less than 75% you will slowly and painfully suffocate them.   Never use plastic tanks, as they don't hold heat or humidity well. Jumbo hermit crabs require about 5 gallons (19 L) of space per 1 crab. The rule of thumb is at least half the height of your tank in order to provide them the correct depth to burrow and dig tunnels. Proper substrate depth will help with fighting or stress with your crabs and also help maintain a proper humidity in your tank.  Your crabs need to burrow into during molting, which is the process that allows them to grow. Purchase play sand from a home repair store. The "hermit crab" sand from pet stores often has harsh chemicals and the play sand is cheaper at the home improvement store. You'll want to mix the playsand and Ecoearth to a consistency that is similar to a sand castle. For land crabs, leaf litter and bark make a nice addition to your substrate but are not necessary so long as your tank has a base of sand and eco earth. Give your tank at least 3-5 large empty hermit crab shells for every 1 crab. These shells provide shelter and housing for the crabs as they grow and can be purchased from pet stores. You can also add a natural and untreated hollow log for both climbing and shelter.  Swap out the initial shells for bigger ones as the crabs grow larger. Never use painted shells—they are dangerous and can be toxic to your crabs. Purchase branches and vines at pet supply stores or dollar stores for the crabs to climb on. Avoid any conifers and do not ever use metal inside the tank. Hermit crabs need a range of temperatures since they are cold-blooded. They rely on being able to move across their environment to adjust their body temperature. Place a UTH under one side of your heater (it doesn't matter which one) to create a warmer end and provide such a range. Afterward, add thermometers—one for the cool end and one for the warmer end. Purchase UTHs from pet stores or online suppliers. Set the tank temperature with a temperature controller and monitor it regularly. If you can't read the temperature directly, use an LCD thermometer. A small dip in temperature at night is normal so long as it doesn't go below 72 °F (22 °C). Remember that extended periods of cool temperatures can make your crabs sick and even die.  Keep an eye on the temperature daily. The temperature at the cooler end of the tank should be about 70–72 °F (21–22 °C), and up to 82 °F (27.8 °C) at the warm end. Although nighttime temperature dips are normal, tank temperature should never remain at 72 °F (22 °C) for long periods of time. Place your tank in a location that exposes crabs to a standard light cycle. You can also install overhead lights if your tank doesn't get enough light. Always ensure the bulbs aren't covered by a plastic barrier or glass and replace them every 12 months. Just remember that crabs need a 12-hour cycle of dark and light for proper molting.  Don't set the tank in direct sunlight. A glass tank will amplify the heat of the sun and can overheat very quickly, which can cause heat damage and illness to your crabs. If your crabs get sufficient daytime light, you can skip the tank lights. Install UVB bulbs to provide both light and heat for your crabs. This is a great option if you're having trouble getting the tank temperature hot enough. If you need to heat your crabs at night, use bulbs that don't release UV rays. Hermit crabs are scavengers and require a very diverse diet—they cannot live on commercial foods alone. Offer daily servings of seaweeds and algae, proteins in the form of meats, calcium-rich foods, organic earthworm castings, chitin sources such as mealworms and shrimp, and fresh fruits and vegetables. Your crabs also need cellulose, which is found in cork bark, grape wood, and cholla wood.  Give your crabs chopped coconuts, papayas, mangoes, and any fruits that are common in their native habitat. For meat and seafood, you can serve them raw or cooked and with or without bones. Just make sure there is no butter, salt, or sauce on them. Always place meat into the habitat at night and remove it in the morning to prevent flies or scavengers. Always keep your tank in a room that remains at an acceptable and steady temperature. This means away from vents that release cold air and away from windows and outdoor locations that expose them to direct sunlight. Keep your habitat away from pets and areas where you use cologne, hairspray, and room deodorants.

Summary:
Choose a tank with 15 gallons (57 L) of space per 2 crabs. Place 6 to 10 inches (15 to 25 cm) of play sand  mixed with EcoEarth onto the bottom. Provide your crabs with hiding places and objects to climb on. Install a under tank heater (UTH) on one side of your tank, NEVER under the substrate. Keep the tank temperature between 75 to 82 °F (24 to 28 °C) during the day. Expose your hermit crabs to a normal 12-hour cycle of light and dark. Feed your hermit crabs dark vegetables, meats, chopped fruit, and seeds. Put your hermit crab habitat in safe and stable environment.