Black Longspine Urchin

My species/animal is an invertebrate: Black Longspine Urchin (Diadema setosum). It is a peaceful species that is reef-safe, admired for its jet-black body, extremely long thin spines, bright orange eye spot, and striking ability to graze algae effectively while adding dramatic appearance to reef tanks.

Males typically cannot be distinguished from females, as this species is not sexually dimorphic, while juveniles are smaller with shorter spines and less vibrant coloration. They reach about 8–10 inches across including spines (with the body itself around 3–4 inches) and should be housed in aquariums of at least 75 gallons.

Provide ample live rock for grazing and hiding during the day, with open swimming space for their long spines to move freely. Maintain stable water parameters (salinity ~1.020–1.025, temp ~72–79 °F, pH ~8.1–8.4). A secure lid is recommended, not because they jump, but to prevent them from dislodging equipment or crawling into overflow areas.

Diet should consist of natural algae (film, hair, and macroalgae) supplemented with dried seaweed (nori), spirulina, and sinking herbivore pellets. They may also scavenge leftover meaty foods like mysis or brine shrimp if available. With proper care, this urchin makes a hardy, eye-catching, and useful addition to the aquarium, acting as both a grazer and a unique display invertebrate.

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.