Aquarium Livestock Pet Care Guides

Hermit Crabs

Natural Habitat

Indo-Pacific, Atlantic

Tank Temperature




Specific Gravity


Tank Requirements

Extra shells must be provided for growth and for the crabs to change into. Water changes must be done regularly to replenish minerals and allow for exoskeleton construction.


Varies with species. Some are primarily algae-eaters while others are scavengers or carnivores. Food should be provided without leaving excess behind to decompose.


Varies with species. Most are peaceful but will feed on a dead or dying tankmate. Larger crabs may prey on some inverts or may even catch small fish. Underfed crabs or crabs without empty shells provided may prey on snails.


Most are Community Safe, Invert Safe and Reef Safe with caution.

Species Overview

Hermit Crabs are some of the most well-known crustaceans, thanks to their popularity in the media as well as in the pet trade. Land species are popular pets and are sold in beach towns across the country. The hermit crabs available for saltwater aquariums are similar, but live their entire lives underwater.

Most hermit crabs are scavengers. Some smaller hermit crabs will feed on algae, such as nuisance hair algae, while larger hermit crabs are scavengers and carnivores. Most hermit crabs are opportunistic - they will not actively hunt for a fish or active invertebrates, but will prey on sick, dead, or dying fish and inverts. Only the larger hermits like those from the genuses Aniculus, Dardanus, Paguristes, and Petrochirus are a real threat to healthy, larger tankmates or to corals. Calcinus, Clibanarius, and some Paguristes are some of the most common "clean-up crew" hermit crabs recommended for algae control and detritus pick-up. Hermit crabs that are underfed may also be a greater threat to tankmates like snails and other invertebrates.

Hermit Crabs have soft abdomens and use empty snail shells to protect their bodies. As with other crustaceans, hermit crabs must molt to grow. When they molt, they crawl out of their shell homes and shed their exoskeleton. As they grow larger, they need to find new, larger shells to keep their soft abdomen protected. Provide larger empty shells in the aquarium for the hermit crabs to move into, or they may make their own by killing the snail inside. Without extra shells, individuals may still molt and then be left extremely vulnerable to predators.

Crustaceans benefit from iodine and mineral supplements to help form a healthy, hard exoskeleton. Regular water changes with high quality salt mixes usually provide enough, but extra supplements may be needed in reef tanks or in tanks with heavy invertebrates loads that use up iodine and other minerals rapidly.

We always suggest that you do further research before adding a new pet to your tank. What we have provided for you are guidelines and suggestions. If you have any further questions or concerns, please contact our fish room at 717-299-5691 ext. 1213 or

Recommended Items

Iodine Supplements
Extra Shells