Staghorn Hermit Crab

Manucomplanus varians

Origin	Eastern Pacific — Gulf of California, Mexico
Maximum Length	1 inch (crab); the hydrocoral "shell" is larger
Minimum Tank Size	20 gallons
Reef Compatibility	Yes — peaceful and reef safe

Behavior

The Staghorn Hermit Crab is one of the most extraordinary hermit crabs in the hobby. Rather than swapping into progressively larger snail shells like most hermits, it lives inside a shell that becomes overgrown by a golden, antler-like colonial hydrocoral (Janaria mirabilis). The hydrocoral grows in step with the crab, continuously enlarging its living quarters so the crab never has to move house. This unique partnership benefits both: the crab gains a self-expanding, protective home while the hydrocoral gets mobility and access to food. The crab is small, peaceful, and nocturnal, plodding across the rock and sand at night to scavenge. Its bizarre branching “staghorn” home makes it a true showpiece oddity.

Diet & Feeding

Omnivore/scavenger. Feeds on detritus, algae, and meaty leftovers. In captivity offer sinking pellets, dried seaweed, and small bits of fish or shrimp. The hydrocoral colony also captures fine plankton, so occasional phytoplankton/zooplankton dosing benefits the pair.

Cautions

Do NOT try to remove the crab from its hydrocoral home — the two live as one unit and separating them will kill the colony. Peaceful and reef safe, but small and slow; keep away from aggressive fish or predatory tank mates. Provide gentle-to-moderate flow and stable parameters to keep the hydrocoral healthy. Sensitive to copper and poor water quality. A specialty animal — buy only healthy, active specimens.