For a novice or beginner, the dwarf blue leg hermit crab (also known as the blue-legged hermit crab, tricolor hermit crab, blue leg reef hermit crab, and equal-handed hermit crab) is widely regarded as one of the easiest pet species to take care of in captivity.
As blue leg hermit crabs are so small, the legs are likely all you’ll see. As the name suggests, they have bright blue legs, usually spotted with yellow or orange stripes.
Another striking visual element of this species is that, unlike most hermit crabs, both chelipeds are the same size. This earned them another unofficial name, the equal-handed hermit crab.
The blue leg hermit crab is among the smallest species in the world. The average size of this hermit crab is just under 1 inch, which is why they’re often referred to as dwarf hermit crabs.
Blue leg hermit crabs live in shallow waters in the Atlantic and Pacific oceans. PeerJ said you’ll likely encounter blue leg hermit crabs in the Florida Keys because they gather near coral reefs.
They’re considered an aquarium clean-up crew due to their preference for eating algae.
Like most hermit crabs, blue leg hermit crabs are nocturnal animals. They’ll usually wake up, emerge from the substrate around dusk, and remain active for most of the night.
Dwarf Blue Leg Hermit Crab Personality
The blue leg hermit crab (Clibanarius tricolor) is semi-aggressive. This doesn’t mean you’ll be pinched by a blue leg hermit crab. Even if the animal clamps its chelipeds on your finger, it’s unlikely to hurt.
As conflict may arise, be selective about other animals you keep with blue leg hermit crabs. For example, they may attack sea snails and attempt to steal their shells.
The aggressive tendencies of blue leg hermit crabs are balanced by the entertainment they provide. They’re active and curious creatures that scuttle around the base of the aquarium.
Hermit crabs are social animals that live in colonies in the wild, and the blue leg hermit crab is no exception. Don’t adopt a single hermit crab because it’ll grow lonely and stressed.
Introduce a minimum of 3-4 hermit crabs to a tank for companionship and emotional support.
The likeliest cause of conflict is territory and shells. If you provide a tank large enough for everyone, and a wide selection of spare shells, they should all live in harmony.
Can Blue Leg Hermit Crabs Live with Other Hermit Crabs?
You can pair blue leg hermit crabs with other aquatic hermit crabs, but this isn’t advisable if you’re a novice owner. Due to their small size, they feel safer and more secure around their species.
Equally, conflict is likelier to erupt if you place a larger but more docile hermit crab with the blue-leg hermit crab. The desire for new shells may encourage this, and a blue leg hermit crab will not be deterred by any size discrepancy between itself and a rival.
If you wish to keep your blue leg hermit crabs with different species, look for a pet that prefers a different shell style. This will minimize the risk of conflict. The Halloween hermit crab will add another aesthetic dimension to your tank and not fight with a blue leg.
Can Blue Leg Hermit Crabs Live with Fish?
Blue leg hermit crabs can peacefully coexist with docile fish with the same water requirements. This can benefit the fish, as hermit crabs eat algae and keep the tank clean.
Guppies, mollies, and tetras are the best fish to keep with blue leg hermit crabs. Avoid betta fish and other aggressive species, as this will lead to regular fights and clashes.
Don’t keep sea snails in an aquarium with blue leg hermit crabs, especially cerith snails.
Aquarium Requirements for Blue Leg Hermit Crabs
Before bringing blue leg hermit crabs home, set up an aquarium that meets their needs. This tank must be large enough to accommodate various aquatic animals, with the right water and enrichment.
Tank Size
Finding the ideal tank size for blue leg hermit crabs keeps them calm and prevents territorial battles. If blue leg hermit crabs have minimal space, they’re likelier to squabble.
How many blue leg hermit crabs per gallon?
Around 3-4 gallons per blue leg hermit crab should keep everyone happy. This means you need a 20-gallon tank for 4 hermit crabs.
If you’re also keeping fish, you don’t necessarily need to increase the tank size. Hermit crabs will favor the bottom of the aquarium, and fish will swim above their heads.
What To Put in The Tank
Aside from water, blue leg hermit crabs need the following in their tank:
- Substrate for burrowing under, like sand.
- Hiding places, such as rocks. Live rocks will also provide algae for grazing.
- LED aquarium lights.
- Water filter.
- Water heater.
- Hydrometer to measure water salinity.
Coral reefs are optional. Blue leg hermit crabs enjoy having coral in a habitat as it’ll be more natural and authentic but are likely to eat and otherwise damage them.
Kind of Water
From temperature requirements to water salinity and hardness, you provide blue leg hermit crabs with the right aquatic environment. This table outlines the ideal living conditions:
| Water temperature: | 71 – 80OF |
| Water density (aka Specific Gravity, or SG): | 1.018 – 1.025 |
| Water power of hydrogen (pH): | 8.0 – 8.5 ppm (parts per million) |
| Water carbonate hardness (KH): | 8 – 16 ppm |
| Water nitrates: | Below 20 ppm |
The blue leg hermit crab is pretty hardy and can adapt and survive slightly outside these parameters, but these should be considered optimal conditions.
Can Blue Leg Hermit Crabs Live Out of Water?
Like all aquatic animals, blue leg hermit crabs can’t breathe when out of the water for long. Their gills will scar and eventually close without water, resulting in suffocation.
You can take blue leg hermit crabs out of the water for a few minutes while transferring them to a temporary tank for cleaning, but never leave them exposed to the open air for more than a few minutes.
Can Blue Leg Hermit Crabs Live in Freshwater?
Blue leg hermit crabs are a saltwater species. They can tolerate freshwater temporarily, but this isn’t an environment where they’ll thrive.
What Do Blue Leg Hermit Crabs Eat?
Blue leg hermit crabs are omnivores, but they typically prefer meatier foodstuffs than terrestrial hermit crabs, who prefer fruit and vegetables.
They’ll sustain themselves on hair algae and dead tissue shed by any fish in the tank, keeping the aquarium clean. While they have carnivorous tendencies, blue leg hermit crabs won’t eat live fish.
Blue leg hermit crabs will also eat fish flakes that sink to the bottom of the tank. Provide occasional shrimp, meat leftovers, and dried seaweed to treat hermit crabs.
Do Blue Hermit Crabs Need New Shells?
Always provide spare shells in an aquarium to ensure they have a spare vessel if the one they wear becomes damaged because this will reduce the risk of infighting.
Hermit crabs aren’t born with shells, so they always look for the best external shell. This means they may clash over what’s considered a superior option.
Blue leg hermit crabs warn that they’re preparing to fight for a shell by raising their foremost walking legs and antennae. It’ll raise all 4 walking legs and balance on its shell when it’s particularly aggressive.
This warning will be proceeded by the aggressor retreating behind another hermit crab and shaking its shell, attempting to dislodge it. If successful, the agitator will claim the shell.
If the aggressive hermit crab doesn’t like this new shell, it’ll immediately evacuate and try an alternative. If it likes the new shell, it allows the evicted hermit crab to move into the vacated shell.
What Shells Do Blue Hermit Crabs Like?
Blue leg hermit crabs prefer the shells of cerith snails. These are an appropriate size and weight for a blue leg hermit crab and have a round opening they find easy to enter.
If you buy different shells for blue leg hermit crabs, ensure they have a round opening and are no larger than 1.5 inches. Unfortunately, anything bigger will be too large and heavy.
How Often Do Blue Hermit Crabs Molt?
Most hermit crabs molt their exoskeleton at least every 12-18 months.
Blue leg hermit crabs are so small that molting can happen more frequently. Juvenile hermit crabs always molt more frequently due to the need to increase their size.
Why are My Blue Leg Hermit Crabs Dying?
Although blue leg hermit crabs have a short lifespan in captivity, it’s still disappointing when they die. Before assuming the hermit crabs have perished, ensure they aren’t molting.
If you’re certain the hermit crabs have died, check the water in the tank. Inappropriate water density or temperatures are frequently responsible for hermit crab mortality.
Monitor the cleanliness of the fish tank. While hermit crabs are efficient cleaners, some decomposed food or organic matter may escape their attention.
While the Journal of Crustacean Biology explains that ammonia alone won’t kill hermit crabs, it can damage the internal organs and gills, increasing the risk of secondary illness.
It also remains possible that the hermit crabs died due to stress. They can struggle with life in captivity, and even with the best of intentions, you may not be able to sustain every hermit crab in your care.
