Don’t use a plastic enclosure for hermit crabs, as they do not maintain temperature and humidity well. Glass lids are best to control humidity, but make sure they have holes for ventilation.
Make sure that your aquarium is big enough to house the group of hermit crabs, to avoid overcrowding that can lead to fighting or stress.
Never use painted shells, because paint contains toxins that can harm the crabs. If the crabs don’t have enough shells to choose from, they might get aggressive and try to steal shells from each other.
Hermit crabs usually eat the skin that they shed. Leave the skins in the tank if you see them, because it is a good source of calcium for them.
Make sure the tank has at least 6 in (15 cm) of substrate at all times to accommodate medium-sized crabs.
Clean the rocks and driftwood in warm water with mild dish soap, rinsing them off thoroughly before you put any pieces back in. Store away anything you are switching out to swap in again the next time you clean the tank.
Use dishes that are heavy enough, so that when the crabs climb up them, they won’t tip over. Get a packet of marine salt at a pet shop or aquarium supply store and follow the directions to mix it with water to create the salt water.
Crabs are not picky about food. You can try feeding them just about any kind of fresh fruits and vegetables and dry snacks to see what they like. Consult the directions on packets of fish food to see how much you should feed the crabs.
You can adjust the temperature by adding or removing heat sources, or moving the aquarium to different parts of your house that are cooler or warmer. You can adjust the humidity in your tank by putting in smaller or larger water dishes, adding coconut husk fiber to the substrate, or installing a mister or humidifier. Heat just one side of your aquarium to allow the hermit crabs to move around to where they feel most comfortable.
If you see your crabs losing legs, they probably have a mite infestation. Clean the habitat and place the crabs in their salt water dish to bathe them. You should also change the substrate in the tank after a mite infestation. Replace it with fresh marine sand and coconut husk fibers.
Always supervise children if they are handling the crabs. Don’t handle your crabs the first few days after you bring them home. Allow them time to adjust to their new habitat. Feed your hermit crabs well and they are less likely to pinch you. Sometimes excessive pinching means they are grabbing onto anything because they are looking for food. Wash your hands with hand soap and warm water before and after handling your crabs.
You can purchase water testing kits at an aquarium store or online.
Never replace all the water at once in your aquarium, or you will upset the balance of the levels.
You can keep saltwater marine hermit crabs with many other species of tropical saltwater fish because their tank requirements are very similar.
Small marine hermit crabs can survive on leftover fish food from any other fish in your aquarium, as well as algae and plants that grow in the tank.
