Diadema setosum (Long Spine Urchin) Sea urchin

The Long-spined Sea Urchin ( Diadema setosum ) is the most powerful herbivore available for intensive algae control in reef aquariums. Its black, spherical body is surrounded by long, thin, rigid spines that can reach 25–30 cm in length. Remarkable effectiveness: it can restore completely green rocks to a pure, white limestone in just a few weeks.

Warning: The thorns are stinging and easily pierce the skin. Handling with thick gloves is mandatory.

His role in the baccalaureate

Intensive grazer — scrapes away unwanted encrusting, filamentous, and coralline algae with its teeth (Aristotle's Lantern). An ideal solution for tanks with severe algae infestations resistant to other cleaners.

Recommended conditions

• Temperature: 24–27°C
• Salinity: 1.024–1.026 — sensitive to sudden drops
• pH: 7.8–8.4 (normal natural day/night fluctuation in a reef tank)
• Alkalinity: 8–11 dKH — Calcium: 400–450 ppm
• Minimum volume: 200L — stable and well-secured rocks required

Behavior

Primarily nocturnal. Can destabilize poorly attached frags with its long spines. Ensure all pump inlets are protected by grates. Lifespan can exceed 5 years.

Compatibility

Harmless to corals and fish. Avoid with triggerfish and large predatory wrasse.