Pencil Urchin (Eucidaris tribuloides)

The Pencil Urchin is a unique and hardy marine invertebrate, named for its thick, blunt spines that resemble old-fashioned pencils. Unlike some other urchins, it is more robust and capable of navigating rocky and sandy substrates with ease. This nocturnal species is an efficient scavenger, helping to keep the aquarium clean by consuming algae, detritus, and leftover food.

Size:
Can grow up to 4-5 inches in diameter, including spines.

Aquarium Size:
A minimum tank size of 30 gallons is recommended, with plenty of rockwork for grazing and shelter.

Temperament:
Generally peaceful but can be somewhat destructive in reef tanks by knocking over loose corals or dislodging rock structures while moving.

Reef Compatibility:
While not inherently harmful to corals, the Pencil Urchin may accidentally damage or displace them when searching for food. It is best suited for larger, stable reef setups or fish-only aquariums.

Diet:
Feeds on algae, detritus, and leftover food but may require supplemental feeding with algae sheets or sinking pellets if natural food sources are insufficient.

Tank Setup & Care:

• Requires stable rock structures to prevent toppling.
• Prefers moderate to high water flow.
• Nocturnal, often more active during the evening and nighttime hours.
• Should not be housed with aggressive fish that may nip at its spines.

Disclaimer:
Aquarium Arts cannot guarantee compatibility with your current fish or the fish you buy and cannot be held liable for fish lost due to aggression.