Pithos Crab

Pitho Crab: The Ultimate Reef Algae Eater If you are battling stubborn nuisance algae in a saltwater aquarium, the Pitho Crab (Pitho lherminieri)—often called the Pitos crab or Caribbean decorator crab—is one of the best hidden gems in the marine hobby. Unlike some larger, more opportunistic crabs, these small, nocturnal invertebrates are celebrated for their peaceful demeanor and voracious appetite for problematic reef film and turf. Natural Habitat and Appearance Native to the warm tropical waters of the Atlantic Ocean, particularly around the Caribbean and the Gulf of Mexico, Pitho crabs are master camouflage artists. They feature an off-white to sandy-beige carapace, frequently speckled with subtle motes of olive green or earthy brown that mimic the rocky substrates they call home. In the wild, they are technically part of the decorator crab family and will occasionally attach small bits of algae or debris to the fine hairs on their legs to blend perfectly into their surroundings. Diet and Reef Compatibility What makes the Pitho crab a prized addition to a cleanup crew is its highly specific diet. While many reef keepers turn to Emerald Crabs to solve algae issues, Pitho crabs are often considered more reliable and less aggressive. They excel at consuming: Hair Algae (GHA): They will systematically pick through thick tufts that snails ignore. Bubble Algae: They can safely pop and consume valonia without causing massive spore outbreaks. Filamentous and Turf Algae: Their small, precise claws are perfectly adapted for scraping rocks clean. They are overwhelmingly reef-safe, showing zero interest in corals, clams, or small fish. Because they remain relatively small, they can easily navigate tight rockwork without bulldozing unglued coral frags. Quick Reference Guide Care at a Glance Common Names: Pitho Crab, Pitos Crab, Caribbean Decorator Crab Scientific Name: Pitho lherminieri Temperament: Peaceful; reef-safe Maximum Size: Approximately 1 to 1.5 inches Diet: Herbivorous/Omnivorous (Primary focus: nuisance algae) Minimum Tank Size: 10 gallons Water Parameters Temperature: 72°F – 78°F (22°C – 26°C) Salinity / Specific Gravity: 1.023 – 1.025 pH: 8.1 – 8.4 Alkalinity: 8 – 12 dKH Husbandry Tips Acclimation: Like all marine invertebrates, Pitho crabs are highly sensitive to rapid changes in salinity and copper. Use a slow drip-acclimation method over 1 to 2 hours before introducing them to the display tank. Supplemental Feeding: If your aquarium becomes pristine and lacks natural algae, ensure you supplement their diet with dried seaweed (nori) or sinking algae pellets to prevent starvation. Molting Support: Maintain adequate calcium and trace iodine levels in the water. This supports their shedding process, allowing them to safely grow a strong new exoskeleton. Provide plenty of dark rock crevices where they can hide while their new shell hardens.