Mathae's Urchin

Geographical Origin and Habitat: Widespread throughout the tropical Indo-Pacific reefs. Commonly found in shallow coral reef flats, exposed rocky shores, and tidal pools.

Taxonomy: Member of the Echinometridae family. Features an oval-shaped test (shell) with stout, conical spines. Reaches a diameter of about 5-8 cm.

Social Behavior: Solitary burrower. Uses its spines and teeth to physically erode limestone rocks to create snug-fitting cavities. Mostly active during the night.

Coloration and Sexual Dimorphism: Spine coloration varies from black, dark brown, and olive green to reddish-purple, often with pale tips. No external sexual dimorphism.

Tank Setup: Mature marine aquarium with stable rockwork. **Secure all live rocks** to prevent rockslides caused by its boring and burrowing activities.

Diet and Feeding: Herbivorous grazer. Feeds on coralline algae, microalgae, and turf algae. Supplement with dried seaweed (nori) sheets if necessary.

Water Quality: Specific gravity 1.023-1.025, pH 8.1-8.4, temperature 22°C-27°C. Sensitive to elevated nitrate and phosphate levels.

Compatibility and Tankmates: Safe with corals. Avoid housing with urchin predators, including large triggerfish, pufferfish, and predatory wrasses.

Aquarium Breeding: Broadcast spawner, releasing eggs and sperm. Reproduction is highly unlikely in home aquariums due to the pelagic larval stage.

Risks and Diseases: Bacterial infections can occur if spines are broken. Highly intolerant to copper medications and sudden changes in water density.