Sally Lightfoot Crab

Sally Lightfoot Crab: The Nimble Scavenger

The Sally Lightfoot Crab (Percnon gibbesi) is a popular and effective member of the marine aquarium cleanup crew. It is known for its extremely flat carapace and lightning-fast, nimble movements, which allow it to dart across rockwork and squeeze into tight crevices, earning it the alternative common name of Nimble Spray Crab.

Native to the Western Atlantic, Caribbean, and parts of the Indo-Pacific, this crab is easily identified by its brown or tan body, often accented with vibrant orange or yellow rings on its leg joints. It typically grows to a manageable size of 3 to 4 inches (7.5–10 cm) across the leg span.

The Sally Lightfoot Crab is an excellent scavenger and a voracious algae eater, with a particular appetite for pesky filamentous hair algae. While generally easy to care for and hardy in stable conditions, its temperament changes as it matures, requiring careful consideration for tank compatibility.

Diet & Compatibility:

• Diet: The Sally Lightfoot Crab is an Omnivore and an opportunistic scavenger. Its primary diet in the aquarium should be algae and detritus (uneaten food and waste).
• Feeding: In very clean tanks, its diet must be supplemented with dried seaweed (nori), spirulina pellets, or occasional small meaty foods like mysis shrimp. A varied diet and high calcium/iodine levels are important for successful molting.
• Reef Compatibility: Reef Safe With Caution. Young specimens are typically harmless and excellent janitors, but as the crab grows larger and more aggressive, it can become a threat. It may prey on small, sleeping fish, tiny snails, or dwarf hermit crabs if insufficient food is available. It is generally safe with healthy, established corals.
• Temperament: Semi-Aggressive / Opportunistic. While usually peaceful, larger crabs may catch and eat small or slow-moving tank mates. It is best suited for tanks with active, fast-moving fish and robust invertebrates.
• Aquascaping: Requires an aquarium of at least 20–30 gallons with ample live rock structure. Its flat body is perfectly suited for hiding and cleaning in crevices. A secure, tight-fitting lid is highly recommended, as they are excellent climbers and potential escape artists.
• Molting: Like all crabs, it sheds its exoskeleton (molting) to grow. Adequate calcium and iodine are crucial for forming a new, hard shell. Do not remove a molted shell, as the crab may eat it to recover essential minerals.

Quick Facts

• Scientific Name: Percnon gibbesi
• Primary Common Name: Sally Lightfoot Crab
• Other Common Names: Nimble Spray Crab, Short Crab, Urchin Crab
• Origin: Western Atlantic, Caribbean, Indo-Pacific (Widespread)
• Max Size: 3–4 inches (7.5–10 cm) leg span
• Temperament: Semi-Aggressive / Opportunistic
• Diet: Omnivore (Algae and Detritus scavenger)
• Care Level: Easy
• Minimum Tank Size: 20–30 Gallons
• Reef Compatibility: With Caution (May prey on small invertebrates and tiny fish)