Sally lightfoot or spray crab — Sally Lightfoot Crab (Percnon gibbesi) M

Overview

The Sally Lightfoot Crab, also known as the spray crab, Percnon gibbesi, is a striking, fast-moving marine crab prized for its bright colouring, long legs and energetic personality. This medium-sized specimen is a fantastic choice for aquarists looking to add a unique invertebrate to a marine setup. It is best known for its grazing behaviour and constant activity, often seen picking at rockwork, glass and algae-covered surfaces throughout the day.

Unlike many crabs that are best described as purely decorative, Percnon gibbesi is an engaging and useful addition to the aquarium. It can contribute to algae control and will happily forage for leftover food, making it a practical choice as well as an attractive one. While generally peaceful, it is still a crab and should be housed with care, especially around very small tank mates, delicate invertebrates and freshly molted animals.

At Tropical Fish Co, we supply healthy marine livestock with a live arrival guarantee and fast UK delivery, so your new crab arrives in excellent condition and ready to settle into its new home.

Care at a Glance

Origin & Natural Habitat

Percnon gibbesi is found in warm marine waters across the Atlantic and Mediterranean regions, including rocky shorelines, reef edges and wave-battered coastal zones. In nature, it is a highly agile crab that lives among crevices, boulders and surge channels where it can dart quickly to safety. Its flattened body and long legs are well adapted to clinging to rough surfaces and moving rapidly over uneven rock.

This natural habitat explains much of its aquarium behaviour. Sally Lightfoot Crabs are most comfortable in tanks with plenty of live rock, hiding places and open surfaces for grazing. They are not sedentary animals; they are active explorers that prefer to roam and pick at surfaces rather than remain hidden all day. A mature marine environment with stable water chemistry closely mirrors the conditions they experience in the wild.

Tank Setup & Water Parameters

A well-established marine aquarium is essential for keeping Percnon gibbesi successfully. As with most marine invertebrates, stability is more important than chasing exact numbers. Provide a tank with plenty of rockwork, caves and ledges, along with secure gaps and a tightly fitting lid, as these crabs are capable climbers and may attempt to leave the aquarium if given the chance.

Because this species is active and can be territorial in limited space, a minimum of 100 litres is recommended, with larger systems preferred if keeping it with fish or other invertebrates. Strong filtration, good oxygenation and regular maintenance will help maintain the clean, stable conditions this crab needs. Moderate water movement is ideal, especially around the rockwork, but avoid blasting the crab directly with strong flow at all times.

Ideal marine parameters are a temperature of 22–26°C, salinity of 1.023–1.025, and pH between 8.1 and 8.4. Ammonia and nitrite should always be zero, and nitrate should be kept as low as practical through routine water changes and efficient filtration. As with all crustaceans, avoid sudden changes in salinity or temperature, as these can cause stress and moulting problems.

Rocky décor is especially important. Live rock provides both grazing surfaces and natural shelter, while also supporting beneficial microfauna that the crab may pick at. Fine sand is not essential, but a mixed reef substrate with plenty of hardscape works very well. Ensure there are no sharp edges or unstable rock piles, as this species is quick and may climb over structures repeatedly.

Feeding Guide

Sally Lightfoot Crabs are omnivorous scavengers with a strong preference for algae and biofilm, but they should not be relied upon to survive on algae alone. Offer a varied diet that includes marine algae, sinking herbivore pellets, spirulina-based foods, frozen mysis, chopped shellfish, krill and other suitable meaty marine foods in moderation. They will also consume leftover fish food and detritus from the substrate and rockwork.

Feed small amounts several times per week, adjusting based on the age of the aquarium and the amount of natural grazing available. In a mature reef or fish-only system with plenty of algae growth, the crab may need less supplemental feeding than in a very clean tank. A varied diet helps support colour, moulting and long-term health.

Like all crabs, Percnon gibbesi requires calcium and trace minerals to support a healthy exoskeleton. A stable marine environment and a balanced diet will help it moult successfully. During and immediately after moulting, the crab may hide more than usual and should not be disturbed.

Tank Mates / Compatibility

This species is usually best kept with robust marine fish and similarly sized invertebrates. Good tank mates include clownfish, gobies, blennies, wrasses, tangs and other peaceful to semi-active reef fish. It can also work in fish-only marine systems and some reef aquariums, provided the aquarist understands that it is an opportunistic scavenger.

Care should be taken with very small shrimp, tiny crabs, newly moulted invertebrates and slow-moving or delicate species. While many individuals are peaceful, any crab may nip if hungry or if a tank mate is vulnerable. Avoid housing with highly aggressive fish that may harass it, as well as very small ornamental crustaceans that could be viewed as food. In a reef tank, keep an eye on sessile invertebrates and ensure the crab is well fed to reduce unwanted picking.

It is also wise to avoid overcrowding. A crab that feels cramped or underfed is more likely to become bold and troublesome. Plenty of rockwork, regular feeding and stable water conditions are the best ways to encourage natural, manageable behaviour.

Why Buy from Tropical Fish Co

When you order a Sally Lightfoot Crab from Tropical Fish Co, you can buy with confidence. We carefully select healthy marine livestock and pack every order with attention to detail, helping to ensure your animal arrives in excellent condition. Our live arrival guarantee gives you added peace of mind, while our fast UK delivery service helps reduce transit stress and get your new crab into its aquarium quickly.

We understand that marine invertebrates need stable, well-handled transport and clear care information. That is why we aim to provide accurate species guidance, quality livestock and dependable service from order to arrival. Whether you are building a reef display or adding a useful algae grazer to a marine setup, Percnon gibbesi is a fascinating choice that brings movement, character and natural behaviour to the tank.

Choose Tropical Fish Co for healthy stock, expert support and a smooth online ordering experience. With the right setup, your Sally Lightfoot Crab can become a long-lasting and entertaining part of your marine aquarium.