Scarlet Reef Hermit Crab

Scarlet Reef Hermit Crab: The Vibrant Algae Cleaner

The Scarlet Reef Hermit Crab (Paguristes cadenati) is one of the most popular, colorful, and beneficial members of the marine aquarium clean-up crew. This species is immediately recognizable by its bright red legs and claws, which contrast beautifully with its yellow or yellowish-orange eyestalks and a relatively small, orange-red body.

Native to the Caribbean and Western Atlantic, the Scarlet Reef Hermit Crab is highly valued by hobbyists for its voracious appetite for nuisance algae. Unlike some other hermit crabs, which can become aggressive toward tankmates, this species is generally peaceful and is less likely to prey on snails for their shells, provided ample empty shells are available.

Reaching a maximum body size (excluding the shell) of about 1.5 inches (3.8 cm), this crab is suitable for tanks of almost any size and is a hardy, long-lived invertebrate that works tirelessly to maintain a clean environment.

Diet & Compatibility:

• Diet: The Scarlet Reef Hermit Crab is an Omnivore / Scavenger. It is primarily a consumer of algae and detritus. It is particularly effective at grazing on green hair algae (filamentous algae) and is known to consume cyanobacteria (red slime algae).
• Feeding: In a well-established reef with sufficient algae and detritus, supplemental feeding may not be necessary. If algae is scarce, supplement its diet with dried seaweed (Nori), algae wafers, marine pellets, or small pieces of meaty foods like mysis shrimp or brine shrimp.
• Shell Supply: Like all hermit crabs, it requires an ample supply of empty shells of various sizes (with wide, circular openings) to move into as it grows. Failing to provide this will increase the risk of it attacking and killing snails for their shells.
• Reef Compatibility: It is considered Reef Safe. It will not harm corals, although it will walk over them while scavenging. Its relatively peaceful nature makes it one of the best hermit crab choices for a mixed reef tank.
• Temperament: It is Peaceful / Semi-Aggressive (toward other hermits). It is generally peaceful toward fish and other invertebrates, but multiple hermits may compete for shells. It should not be housed with large, aggressive fish (like puffers or triggerfish) that may view it as food.
• Clean-up Role: This crab is an excellent clean-up crew member, consuming nuisance algae and helping to aerate the sand bed as it forages.

Quick Facts

• Scientific Name: Paguristes cadenati
• Primary Common Name: Scarlet Reef Hermit Crab
• Other Common Names: Red Reef Hermit Crab, Red Leg Hermit Crab, Scarlet Hermit
• Origin: Western Atlantic (Caribbean, Gulf of Mexico)
• Max Size (Body): ~1.5 inches (3.8 cm)
• Temperament: Peaceful / Semi-Aggressive (shell competition)
• Diet: Omnivore / Scavenger (Excellent algae and detritus eater)
• Minimum Tank Size: 10 Gallons
• Reef Compatibility: Reef Safe (Must provide extra shells)
• Care Level: Easy