Species description

Care, breeding and tankmates

Invertebrate profile

Diet

Omnivore

They are aggressive herbivores as juveniles, constantly tearing at hair algae, bubble algae, and detritus on the live rock. As they grow larger, they can become more opportunistic and omnivorous, occasionally scavenging for meaty foods. Their diet must be supplemented with seaweed or sinking pellets if algae in the tank becomes scarce.

Ecological role

Scavenger

The Sally Lightfoot Crab serves as an exceptional utility animal for controlling nuisance algae on rockwork. Their flat shape allows them to reach deep into crevices where other herbivores cannot access. By keeping the rocks clean, they promote the healthy growth of beneficial coralline algae and corals.

Life expectancy

3-5 years

Shock sensitivity

They require standard, stable marine water parameters and are sensitive to sudden swings in salinity or temperature. A careful drip acclimation is necessary to prevent osmotic shock upon introduction. Once acclimated, they are extremely hardy, provided water quality is maintained.

Calcium and minerals

High

Robust calcium, alkalinity, and magnesium levels are essential for this crab to successfully build its exoskeleton. Proper reef chemistry supports their frequent molting process as they grow quite rapidly. Inadequate minerals will result in failed molts, leaving the crab vulnerable or leading to immediate death.

Molting

Regular

They molt regularly, shedding an exact, translucent replica of themselves that often startles aquarists who mistake it for a dead crab. During the molting phase, they must hide deep within the rockwork until their new shell fully hardens. Leaving the shed exoskeleton in the tank allows them or others to recycle the calcium.

Reproduction

Oviparous

Captive breeding of Percnon gibbesi is virtually impossible for the home aquarist. They release microscopic planktonic larvae into the water column which require vastly complex feeding and tidal conditions to develop. In an aquarium, these larvae simply become food for corals and fish.

Compatibility & tankmates

Reef safe with caution

While generally reef-safe and excellent cleaners when small, large adults can become aggressive and opportunistic. Fully grown specimens have been known to hunt small sleeping fish or attack other invertebrates if underfed. They should be monitored closely as they grow and housed with appropriately sized, active tankmates.