Black/Purple Shortspine Urchin

Black/Purple Shortspine Urchin — Diadema setosum

The Diadema setosum Black/Purple Shortspine Urchin is a striking reef invertebrate with a dark purple to black body and relatively short, rigid spines. Slow-moving and peaceful, it grazes on algae and detritus across rockwork and sand, helping control nuisance algae while maintaining tank cleanliness. Its unique coloration and spiny texture make it an attractive and functional addition to mature reef systems.

Black/Purple Shortspine Urchins thrive in established reef tanks with stable water parameters, moderate water flow, and abundant grazing surfaces. Introduce only to mature systems to ensure adequate natural food and reduce stress. A minimum tank size of 20 gallons is recommended to provide room for grazing and natural roaming behavior.

Their diet can be supplemented with algae-based foods from Julian Sprung’s Sea Veggies and finely powdered or pellet foods from San Francisco Bay Brand, Hikari, PE, TDO, and New Life Spectrum to support health and vibrant spine coloration. Target feeding encourages active grazing and optimal growth.

Approximate product size: 2"–4" (varies by availability)

We maintain a rigorous, veterinarian-approved quarantine program that includes proactive treatments, careful observation, and daily monitoring to ensure the highest standards of invertebrate health. Our biosecurity practices reduce the risk of any cross-contamination between systems, meaning our livestock are ready for your display tanks.