Pencil Urchin

The Pencil Urchin is a semi-aggressive species that is reef-safe with caution, admired for its thick, blunt spines that resemble pencils, unique radial symmetry, and ability to add unusual texture and movement to reef aquariums. While hardy and striking, they may occasionally knock over loose corals or rocks while foraging, so aquascaping stability is important.

Males typically do not display external differences from females, as the species is not sexually dimorphic, while juveniles are smaller with proportionally thinner spines and may have lighter coloration.

They reach about 3–5 inches in size and should be housed in aquariums of at least 50 gallons, with ample live rock for grazing and hiding spots, as well as a sandy or rubble substrate to mimic their natural environment.

Maintain stable water parameters:

• Salinity: 1.020–1.025

• Temperature: 72–79°F

• pH: 8.1–8.4

A secure lid is not necessary, as Pencil Urchins are not jumpers, but tank rockwork should be secured since their movements can dislodge objects.

Diet: Omnivorous. They feed on algae, biofilm, and detritus, but may also consume sponges, sessile invertebrates, and occasionally corals. In aquariums, supplemental feeding with dried seaweed (nori), macroalgae, sinking pellets, or small meaty foods like mysis shrimp can help sustain them, especially in newer or lower-nutrient systems.

With proper care, the Pencil Urchin makes a hardy, unique, and visually striking addition to aquariums, though best kept in systems where delicate corals and frags are securely placed.

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.