Not furry either, still lovely.
Sally Lightfoot Crab
Percnon gibbesi
Also called Nimble spray crab, Urchin crab, Sally Lightfoot
From Both sides of the Americas and West Africa: the Pacific coast from California to Chile, and the Atlantic from Florida to Brazil and from Madeira to the Gulf of Guinea. Since 1999 it has also settled in the Mediterranean.1
A friendly guide, not veterinary advice. For anything about your pet's health, ask your vet.
At a glance the quick version
Wikipedia gives a carapace width up to 3 cm; LiveAquaria gives a maximum size of 3 in (7.6 cm) without saying how it is measured.
Looks how to spot one
Hard, very flat exoskeleton
A flat-bodied crab built for squeezing into narrow rock gaps. The long legs carry a row of spines along the front edge and are ringed with yellow or orange at the joints, set off by a brownish body.12
Personality what they are like
Quick and alert, darting into crevices at the slightest movement. LiveAquaria rates it semi-aggressive: large adults may grab small fish or invertebrates, so choose tankmates with that in mind.2
Daily activity how busy a day looks
Very active, scrambling over rocks to graze. It does best with lots of rockwork and a decent water flow.2
Grooming and care the hands-on bits
Rated easy. Keep calcium, magnesium, iodine and trace elements at reef levels for healthy moults, and add dried seaweed if the tank runs short of natural algae.2
Home where they are happiest
A larger marine aquarium with plenty of rock to hide in and strong water movement. LiveAquaria gives 72-78 °F (about 22-26 °C), pH 8.1-8.4, dKH 8-12 and specific gravity 1.023-1.025. In the wild it lives among boulders, and in the Caribbean often near sea urchins. No minimum tank size was given by the sources.21
Food basics what goes in the bowl
Wild crabs are plant eaters, which is unusual among crabs. In aquariums it grazes algae and can be given dried seaweed plus some meaty foods if algae is scarce.12
Company who they like around
Usually kept singly in a community tank. Avoid very small fish or shrimp as tankmates once the crab is grown.2
The story where it all began
Henri Milne-Edwards described the species in 1853. It became a familiar reef aquarium algae grazer, and in 1999 it was found for the first time in the Mediterranean, near Linosa off Sicily, where it has since spread to several countries.1
Fun facts for the dinner table
- 1
It is one of very few crabs that eat almost only plants and algae in the wild.1
- 2
Its body is so flat it can slip into rock cracks that look far too thin for a crab.2
- 3
Its larvae drift in the plankton for a long time, which helps explain its very wide range on both sides of the Atlantic.1
- 4
In the Caribbean it is often found living near sea urchins, which earned it the name urchin crab.1
Recognised by the official bits
- Taxonomy (via Wikipedia)
- Described by H. Milne-Edwards in 1853; placed in family Percnidae (formerly Plagusiidae).1
The care rhythm Furry Diary remembers it for you
A typical home-care rhythm for a Sally Lightfoot Crab. It is our own starting plan, not a vet's advice, and you can change every line in the app.
- FeedingDepends on species, many feed from the light and the watervaries
- Salinity checkevery week
- Water testevery week
- Top-upTop up evaporation with fresh RO water, not salt waterevery day
- Water changeAbout 10 to 20% of the waterevery 2 weeks
- Light checkevery month
Owner questions the things everyone asks
How often should I feed my Sally Lightfoot Crab?
Feed your Sally Lightfoot Crab daily, offering dried seaweed as a staple. If algae is scarce in the tank, you can supplement with small amounts of meaty foods a few times a week. Always follow the food label and check with your vet for exact amounts.21 Furry Diary plan
What does a Sally Lightfoot Crab eat, and what should it never eat?
Your crab mainly eats algae and can be given dried seaweed. It may also accept meaty foods like shrimp or fish pieces if algae is low. Never feed it anything with copper or medications, as these can be toxic to invertebrates.21
How much space does a Sally Lightfoot Crab need?
No minimum tank size is given by the sources, but a larger marine aquarium with plenty of rockwork is recommended. The crab is very active and needs room to scramble and graze, so a spacious setup with hiding spots is best.2
What temperature, light or water does a Sally Lightfoot Crab need?
Keep the water at 72-78°F (22-26°C), pH 8.1-8.4, dKH 8-12, and specific gravity 1.023-1.025. Provide strong water movement and moderate lighting for algae growth. Furry Diary's plan suggests weekly salinity checks and a 10-20% water change every two weeks.21 Furry Diary plan
How often should I clean a Sally Lightfoot Crab's home?
Clean the tank by doing a 10-20% water change every two weeks, as per Furry Diary's plan. Also top up evaporation daily with fresh RO water and test water parameters weekly to keep conditions stable. Furry Diary plan
Can a Sally Lightfoot Crab live with others?
Yes, it is usually kept singly in a community tank, but avoid very small fish or shrimp as tankmates once the crab is grown. LiveAquaria rates it semi-aggressive, so choose tankmates carefully.2
How long does a Sally Lightfoot Crab live?
Lifespan varies and is not specified in the sources. Ask a good breeder or an exotic-pet vet for more details on how long your crab may live.
Can I handle a Sally Lightfoot Crab?
Handling is not recommended because this crab is quick and alert, darting into crevices at the slightest movement. It is best to admire it from a distance to avoid stress or injury to both you and the crab.2
Written from the sources on this page, a few checked guides (VCA, ASPCA, RSPCA) and Furry Diary's own starting care plan. A friendly guide, not a vet's advice.
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Where this comes from
Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at support@furrydiary.app and we will fix it.
- Percnon gibbesi (Wikipedia) en.wikipedia.orgused for names, range, size, appearance, diet, history, fun facts
- Sally Lightfoot Crab, LiveAquaria liveaquaria.comused for care level, temperament, water parameters, diet, size, colour
- VCA Animal Hospitals: Feeding times and frequency for your dog vcahospitals.comused for owner questions
- ASPCA: Dog grooming tips aspca.orgused for owner questions
- ASPCA: Cat grooming tips aspca.orgused for owner questions
- ASPCA: People foods to avoid feeding your pets aspca.orgused for owner questions
- RSPCA: What to feed your rabbit rspca.org.ukused for owner questions
Checked 2026-09-30. Text is written in our own words from these sources.