POM POM CRAB (LYBIA SPP) CARE GUIDE
The Pom Pom Crab (Lybia spp.), also known as Boxer Crabs or Cheerleader Crabs, are super cool little creatures loved for their quirky behaviour and those adorable "smiles." These tiny crabs are famous for carrying sea anemones in their claws, using them for both protection and food collection. Native to shallow reefs across the Indo-Pacific, they can be found in places like Hawaii, Indonesia, and Japan.
While their relationship with the anemones is often described as symbiotic, many aquarium keepers see it more like an exploitative arrangement, where the crabs seem to benefit from the anemones far more than they help them. Pom Pom Crabs are peaceful and nocturnal, making them a fun addition to your tank. However, they can be a bit challenging for beginners, so stick with us as we guide you through the best care practices to ensure these little guys thrive.
Common Names
Lybia spp is also commonly known as:
Checkered Pom Pom Crab
Hawaiian Pom Pom Crab
Cheerleader Crabs
Boxer Crabs
Members of the species
It’s exceptionally hard to tell the difference between them.
Lybia tessellata (Checkered Pom Pom Crab)
Lybia edmondsoni (Hawaiian Pom Pom Crab)
Interesting Information
Pom pom crabs are one of the most well-known examples of obligate symbiosis in marine invertebrates:
Defence: They wave anemones to deter predators.
Feeding Tool: They use them to trap food particles.
Kleptoparasitism: The crab often steals most of the food the anemone collects, limiting its growth (resulting in a “bonsai” effect).
Regeneration: If a crab loses one, it can tear the remaining anemone in half to make two, a primitive form of “fragging.”
Lybia’s claw adaptations: are solely for holding anemones they can’t dig or fight with them.
Crabs use grooming behaviour: which involves temporarily “parking” an anemone.
The exact number of Lybia species is debated; taxonomy is still under revision. Some species even swap out smaller anemones for larger ones or steal from other crabs. During grooming or molting, crabs temporarily set aside their anemones but retrieve them carefully. If they aren’t blown away by a current. I’ve seen this happen before, and it’s one of the most common ways they lose their anemones.
They will also use other corals and bits and pieces if they don’t have access to anemone. Quite often they will use zoas.
Physical Characteristics
Pom pom crabs are nocturnal, shy, and mostly peaceful. They rarely fight and are careful not to damage their symbiotic anemones. When disputes do happen (e.g., over hiding spots or anemones), they wave their “pom poms” like boxers rather than engage in damaging combat.
Defence: They wave anemones to deter predators. You can watch some footage here
Feeding Tool: They use them to trap food particles.
Kleptoparasitism: The crab often steals most of the food the anemone collects, limiting its growth (resulting in a “bonsai” effect).
Regeneration: If a crab loses one, it can tear the remaining anemone in half to make two—a primitive form of “fragging.”
Some species even swap out smaller anemones for larger ones or steal from other crabs. During grooming or molting, crabs temporarily set aside their anemones but retrieve them carefully.
Conservation level
Unknown – There is limited data on wild populations, so sustainable and ethical sourcing is recommended. Supporting reputable sellers who follow responsible collection practices is important to minimise environmental impact.
Reputable sellers
Most aquarium stores will carry them. Though they are exclusively wild-caught.
Care Level
Difficulty level: Intermediate (Stability is key)
Temperament: Peaceful, Shy
Lifespan: 1-2 years (sadly not long)
Size: Up to 1 inch (2.5 cm)
Enclosure and Environment
These crabs are quite shy and don’t like being out in the open very much, so make sure you have a lot of cover in your tank, rock work, corals, and macroalgae are the best options. They generally hug the rock work when roaming around. It’s rare to see them out in the open.
Tank Size: 5 gallons for one, 10 gallons for a group of three. They do well in nano tanks with other inverts.
Salinity: 1.023–1.025 SG (Stability is super important!)
PH: 8.1–8.4
Temperature: 72-78°F (22–25.5°C)
Filtration: Standard reef and macro algae tank filtration is enough to keep pom pom crabs happy.
Water Flow: Moderate flow, mimicking shallow reef environments
Lighting: Any reef tank or macroalgae tank lighting will work fine for pom pom crabs. If your corals and macro algae a happy, your crabs will be happy too.
Tank Type: Reef tank or Macro Algae tank with live rock, rubble, and caves they like to feel safe hiding in the rocks. I’ve got a video guides showing how to set up both options below.
Substrate
Any substrate is acceptable; they do not appear to have specific substrate preferences.
Cohabitation & Tankmates
Pom Pom Crabs are peaceful and typically get along with most reef-safe fish and invertebrates. They are best kept with:
Peaceful fish like clownfish, gobies, and blennies
Other small invertebrates such as snails, hermit crabs, and shrimp
Avoid aggressive tankmates such as:
Larger predatory fish (groupers, lionfish)
Aggressive or large hermit crabs and triggerfish
Behaviour
Pom Pom Crabs are nocturnal and shy creatures that spend most of their time hiding or foraging for food. Their claws are specialised for carrying sea anemones, which they use as a form of protection and as a tool for feeding. These crabs do not typically fight with their claws but rather use their anemones to fend off predators or rivals in their territory.
Their fighting style involves "boxing" with their anemones waving them in a display similar to a boxer’s gloves rather than engaging in physical combat.
Diet
Pom Pom Crabs are opportunistic feeders and primarily feed on small particles and detritus. Their symbiotic anemones assist in gathering food, and the crabs will often “clean” their anemones, collecting the food particles trapped by the anemone’s stinging cells. Like all crabs, it’s important to make sure they have calcium in their diet as well, otherwise they will have molting issues.
In a tank with adequate food sources, they will find food naturally. However, for supplementary feeding, you can offer:
Sinking pellets or algae wafers
Frozen mysis or brine shrimp
Nori or microplankton
Feeding Tip: Feed them after lights out since they are primarily nocturnal. But they will come out quite often once they get used to tank feeding time.
Breeding Pom Pom Crabs
Very little is known about the breeding habits of Pom Pom Crabs in captivity, but some species of Lybia have been observed carrying eggs under their abdomen. These eggs will eventually hatch into larvae, but successfully raising the larvae in captivity has not been documented. Pom Pom Crabs reproduce via external fertilisation, and while gravid females can be observed, breeding in home aquariums remains a rare occurrence. I’ve managed to get them to mate and drop their larvae in the tank, but they are eaten or die before long, sadly.
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Molting
Like all crabs, Pom Pom Crabs undergo molting to grow. During this process, they shed their exoskeleton and can be vulnerable to stress and predation. They typically hide when they molt and may temporarily release their anemones. After molting, they retrieve their anemones from their old exoskeleton and carry them carefully back into their claws. If you don’t give them a mixed diet with lots of calcium and have good calcium levels in your water, they will fail to molt and die sadly.