Mexican Hermit Crab

Geographical Origin and Habitat: Endemic to the subtropical Eastern Pacific, specifically the Gulf of California (Mexico). Settles in large colonies within rocky and sandy intertidal tide pools.

Taxonomy: Member of the family Diogenidae. A dwarf hermit crab species with an average adult size of about 2 cm. Occupies small empty gastropod shells.

Social Behavior: Peaceful, highly gregarious, and very active. Forms crowded clusters in tide pools. In aquariums, it constantly crawls over rocks and substrate foraging for algae.

Coloration and Sexual Dimorphism: Body is dark greyish-brown or reddish-brown. Leg joints feature a characteristic, bright orange or reddish band. No visible external sexual dimorphism.

Tank Setup: Suitable for small nano reefs of 5 gallons or larger. Provide plenty of live rock for climbing. Small empty gastropod shells must be added to allow growth.

Diet and Feeding: Herbivore and detritivore. Consumes green hair algae, film algae, diatoms, and leftover fish food. Accepts spirulina wafers and sinking pellets.

Water Quality: Stable marine parameters: SG 1.020-1.025, pH 8.1-8.4, temperature 18-26°C. Highly sensitive to copper treatments and elevated nitrates.

Compatibility and Tankmates: 100% reef-safe. Perfect Clean-Up Crew (CUC) member. Compatible with peaceful fish and corals. May occasionally target small live snails if empty shells are lacking.

Aquarium Breeding: Microscopic larval stages are pelagic and complex, and do not survive standard home aquarium filtration systems.

Risks and Diseases: Low iodine or calcium leading to failed molts. Lack of suitable replacement shells causes high stress. Highly sensitive to copper treatments.