Blue Leg Hermit Crab (Clibanarius tricolor)

The Blue Leg Hermit Crab is one of the most widely used and genuinely effective members of the reef cleanup crew, and a staple of the hobby for good reason. With their striking blue legs and constantly active scavenging behaviour, these small crabs are both a visual delight and a valuable working member of any reef system. Native to the Caribbean and the shallow reefs and seagrass beds of the Gulf of Mexico, C. tricolor is a hardy, adaptable species that congregates in large numbers in the wild, feeding on many types of algae, and that same tireless foraging behaviour translates directly into meaningful cleaning performance in the aquarium. Compact, colourful, reef safe, and beginner friendly, the Blue Leg Hermit Crab is a sensible first addition to almost any saltwater cleanup crew.

Why we love them

• Vivid blue legs and constant activity make them one of the more visually engaging cleanup crew animals; you will always know they are working
• Effective at removing hair algae and detritus, and fair at managing cyanobacteria and film algae; they cover both rockwork and substrate with a preference for rocks
• Small adult size makes them suitable for nano tanks as well as large reef systems
• Hardy, low-maintenance, and beginner friendly; one of the easiest invertebrates to keep successfully
• Can be kept in groups and work well as part of a diverse, multi-species cleanup crew

Suggested parameters

• Temperature: 24 to 26°C (75 to 79°F)
• Salinity: 1.025 to 1.026 SG
• pH: 8.1 to 8.4
• Alkalinity: 8 to 10 dKH
• Calcium: 400 to 450 ppm
• Magnesium: 1250 to 1400 ppm
• Nitrate: 5 to 20 ppm
• Phosphate: 0.03 to 0.12 ppm
• Copper-based medications are immediately fatal to all invertebrates and must never be used

Care and temperament

• Difficulty: Easy
• Temperament: Peaceful toward fish, corals, and most invertebrates; all hermit crabs are capable of targeting snails for their shells, and this is the most important caveat to understand before stocking
• Reef safe: Yes, fully compatible with corals and most ornamental invertebrates; use caution with snail populations
• Minimum tank size: 40 litres (10 gallons); suitable for nano systems
• Spend most of their time on rocks and substrate; a well-established system with healthy algae growth on live rock gives them the best start and the most to work on
• A selection of empty shells in graduated sizes must always be available; without suitable shells to move into as they grow, hermit crabs become stressed, vulnerable, and more likely to target snails

Feeding

Blue Leg Hermit Crabs are self-sufficient scavengers in most established reef systems and require little to no supplemental feeding under normal conditions.

• Grazes naturally on hair algae, diatoms, film algae, cyanobacteria, detritus, and uneaten fish food throughout the day
• If algae levels in the system drop significantly, supplement with algae wafers or sinking pellets dropped in during evening hours to prevent starvation
• Nori sheets clipped near the rockwork are also accepted

Stocking and compatibility

• Avoid overstocking; a horde of hungry hermits that depletes available food sources quickly becomes more likely to target valued livestock; stock conservatively and scale numbers to actual algae load rather than tank volume alone
• One per 10 to 15 litres is a reasonable starting density for a system with moderate algae growth, adjusted based on need
• Peaceful and compatible with most fish, corals, and reef invertebrates
• Cerith snails are particularly favoured targets when hermits are seeking new shells; providing a generous supply of empty shells in the right size range significantly reduces but does not eliminate this behaviour
• Avoid large predatory fish such as triggerfish, puffers, and large aggressive wrasses that will eat small crustaceans

Health and acclimation notes

Blue Leg Hermit Crabs are sensitive to rapid salinity and temperature changes during acclimation. Drip acclimation is recommended, as with all invertebrates, to avoid osmotic shock. Maintaining a healthy supply of appropriately sized empty shells at all times is the single most important ongoing care requirement. Regular water changes help replenish the mineral levels that support healthy exoskeleton development through molting. Copper-based medications must never be used in any system housing this or any other invertebrate.

What you are buying

• You will receive: 1x Blue Leg Hermit Crab (Clibanarius tricolor)
• Leg colouration is vivid blue with orange and red banding; shell colour and pattern will vary depending on the shell currently occupied
• Quantity per order as listed; size is typically half to one inch shell

Drip acclimation is recommended. Empty shells in graduated sizes must be maintained in the system. Copper-based medications must never be used in any system housing this animal.