Dwarf Blue Hermit Crab

Geographical Origin and Habitat: Common in the tropical Indo-Pacific, especially around East Asian coasts (Japan, Taiwan), Indonesia, and the Philippines. Inhabits rocky tide pools and shallow intertidal zones.

Taxonomy: Member of the family Diogenidae. Small body with a soft asymmetrical abdomen protected by empty small gastropod shells. Grows to about 2-3 cm.

Social Behavior: Peaceful and gregarious. Likes to assemble in small groups grazing on rockwork and substrate. May have minor disputes over available empty shells.

Coloration and Sexual Dimorphism: Walking legs are bluish, greyish-blue, or grey-green with bright orange or yellow joints. Small claws. No visible external sexual dimorphism.

Tank Setup: Suitable for small nanoreefs of 5-10 gallons. Provide live rock for climbing and forage. Empty snail shells of various sizes must be added to allow growth.

Diet and Feeding: Herbivore and detritivore. Consumes green hair algae, cyanobacteria, detritus, and fish food leftovers. Accepts spirulina wafers and sinking pellets.

Water Quality: Stable reef parameters: SG 1.020-1.025, pH 8.1-8.4, temperature 22-28°C. Strictly zero copper levels. Sensitive to elevated nitrate levels.

Compatibility and Tankmates: 100% reef-safe. Perfect clean-up crew member. Peaceful towards fish and corals. May occasionally target small live snails (like Cerithium) if empty shells are lacking.

Aquarium Breeding: Spawns microscopic planctonic larvae which are quickly removed by mechanical filtration and protein skimmers.

Risks and Diseases: High stress and mortality if empty shells of the proper size are not available after molting. Highly sensitive to rapid salinity changes.