Pitho Crab (Pitho sp.)

The Pitho Crab (Pitho sp.) is the crab reefers reach for when bubble algae has won. It is a close relative of the Emerald Crab in the same family, but it is more active, grows a little larger, and per animal it clears Valonia bubble algae faster than an Emerald does. It also grazes hair algae, Caulerpa, and Dictyota, and spends the rest of its time picking detritus out of the rockwork. Browse the rest of our saltwater livestock and supplies.

It is a genuinely low-profile animal. Mottled tan and olive, roughly an inch and a half across the carapace when grown, and camouflaged well enough that you will mostly notice the algae disappearing rather than the crab doing it.

Care Guide

• Tank size: 10 gallons and up. What matters is live rock, not volume. It needs grazing surface and crevices to retreat into.
• Mature tank preferred: like most cleanup crew, it does best in an established system that already grows the algae and biofilm it eats.
• Diet: herbivore and scavenger. Bubble algae, hair algae, and detritus first. If the tank gets too clean, feed dried nori on a clip or a sinking algae wafer, which it will take readily.
• Reef safe: yes. It works the rock and leaves corals, clams, and other inverts alone.
• Water: 72 to 78°F, salinity 1.023 to 1.025, pH 8.1 to 8.4. Like all invertebrates it needs stable salinity and zero copper, so drip acclimate slowly.
• Molting: it will shed its shell periodically and leave behind what looks alarmingly like a dead crab. Leave the empty shell in the tank; the crab eats it back for calcium.
• How many: roughly one per 20 to 30 gallons for algae control. Too many in a small tank and they compete once the algae runs out.

Specifications

Compatibility

Safe with corals, clams, and peaceful reef fish, and it pairs naturally with the rest of a cleanup crew. Run it alongside Zebra Turbo Snails for film algae and Nassarius Snails for the sand bed, and the three of them cover most of the work between them.

Two cautions. Large predatory fish, triggers, puffers, and hawkfish will eat crabs, so skip it in those tanks. And like any crab it is opportunistic: a well-fed Pitho ignores tankmates, but a starving one in an algae-free tank may pick at something it should not. Keep it fed once the algae is gone.

Recommended Foods & Supplies

• Dried nori sheets on a feeding clip, its favourite supplemental food
• SFBB Frozen Mysis Shrimp as an occasional protein treat
• Zebra Turbo Snail and Nassarius Snail to round out the cleanup crew
• Browse the full saltwater selection

FAQ

When will these be available?
They are on order and heading our way. Everything we bring in goes through quarantine before it hits the sales floor, so the listing will switch to in stock once they are cleared. Ask in store for the latest timing.

Will it actually eat bubble algae?
Usually yes, and it is the main reason to buy one. Pitho Crabs are more reliable on Valonia than Emerald Crabs. No algae eater is guaranteed, but this is the best odds in a crab.

How is it different from an Emerald Crab?
Same family, different animal. Pitho Crabs are more active, get a bit bigger, and hit bubble algae harder. Emeralds are greener and easier to spot; Pithos are camouflaged and you will rarely see them.

Is it safe with my corals?
Yes, as long as it is eating. It grazes rock rather than coral. The usual crab caveat applies: keep it fed once the tank is clean.

I found what looks like a dead crab. Did it die?
Probably a molt. Crabs shed their exoskeleton whole and it looks exactly like the animal. Leave it in the tank and the crab will eat it back for the calcium.