Rock urchin

The rock urchin (Echinometra mathaei) is a compact Indo-Pacific sea urchin with short, blunt spines, usually dark purple to brown, that wedges itself into a hollow in the rock and grazes outward from there. In the wild it excavates its own burrow in reef rock. In an aquarium it is an effective algae eater with a bulldozing streak, and both halves of that description matter.

Aquarium care

• Body diameter is typically 4 to 6 cm, plus spines.
• A grazing herbivore that works hard on film, coralline and hair algae.
• Will pick up and carry small frags, shells and rubble around on its spines.
• Strong enough to shift unstable rockwork, so secure the aquascape before adding one.
• Needs an established tank with real algae growth or it will slowly starve.
• Very sensitive to copper and to salinity swings; drip acclimate slowly.

Best suited to a fish-only tank with live rock, or a robust reef where corals are glued down and the rockwork is stable. It is a poor choice for a display built around delicate frags. Handle it carefully — the spines are sharp, and the urchin comes off worse in a struggle than you do.

Stock rotates with each shipment, and livestock is available for local pickup at our Lethbridge store. More in the saltwater collection.