Bicolor Sea Urchin

Geographical Origin and Habitat: Tropical Indo-Pacific. Inhabits shallow lagoons, seagrass beds, and muddy reef flats.

Taxonomy: Family Temnopleuridae, genus Salmacis. Spherical body slightly flattened at the poles, covered in moderate-length spines.

Social Behavior: Solitary and peaceful. Often collects debris, algae, and empty shells using its tube feet to cover its body for camouflage.

Coloration and Sexual Dimorphism: Beautiful banded spines showing alternating shades of green and purple or deep red. No visual differences between sexes.

Tank Setup: An aquarium of at least 100 liters with plenty of open rock surfaces and stable hardscape is required. High algae levels are ideal.

Diet and Feeding: Herbivorous scavenger. Consumes hair algae, film algae, and detritus. Supplement with dried nori sheets if natural food sources are low.

Water Quality: Keep reef parameters stable. Monitor specific gravity (1.023-1.025), pH (8.1-8.4), and maintain calcium levels for skeletal health.

Compatibility and Tankmates: Great for reef aquariums. Avoid keeping with predators like large wrasses or triggerfish that might damage the urchin.

Aquarium Breeding: Not documented in home aquariums. Spawning occurs by releasing gametes into open water.

Risks and Diseases: Highly sensitive to rapid changes in salinity and copper levels. Spine loss indicates severe stress, starvation, or water chemistry shock.