Giant Spider Crab

The Giant Spider Crab (Naxioides robillardi) is a semi-aggressive species that is reef-safe with caution, admired for its long, spindly legs, camouflaged body often covered in algae or debris, cryptic coloration, and slow, deliberate movements that give it a prehistoric appearance.

Males typically have slightly larger, more robust claws and longer legs used for posturing or mating displays, while females/juveniles tend to be smaller, more reclusive, and less ornamented.

They reach about 6 to 8 inches in adult size (leg span) and should be housed in aquariums of at least 50 gallons, ideally with low aggression tank mates and minimal competition for food.

Provide ample live rock for climbing and camouflage, a sandbed for stability, and dim or indirect lighting, along with stable water parameters (salinity ~1.020–1.025, temp ~72–79°F, pH ~8.1–8.4). A secure lid is recommended—not for jumping, but to prevent escape via climbing equipment.

Diet should consist of meaty foods like mysis shrimp, chopped seafood, brine shrimp, and sinking pellets, but they will also scavenge algae and detritus. Ensure they are well-fed to avoid opportunistic predation on small inverts or sessile corals.

With proper care, this crab makes a truly eye-catching and unusual addition to larger aquariums, particularly in species tanks or setups designed around cryptic and invertebrate life.

International Aquatics Quarantine & Guarantee: All fish are checked by marine vets, given a formalin bath, and held for 14 days in copper-treated systems. We feed Selcon-soaked food with Kanaplex and Metroplex during quarantine. Unless marked, all livestock comes with our 15-Day Guarantee. You will receive a video of your fish eating before shipment. On request, we also send photos/videos after arrival at IA. Some species are import-to-order (3-10 business days). Many common species are already cleared or near the end of QT.

Several species will be import-to-order and may take anywhere from 3-10 business days to secure. Once your fish is secured, you will be notified, and the quarantine process will then begin.