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Diadema setosum
Care guide, husbandry, breeding, disease, sourcing, and tankmate intelligence on Long Spine Urchin - written by the Fast Aquatics editorial team and cross-verified against vendor records on the live marketplace.
Long Spine Urchin requires a minimum of 55 gallons for healthy adults. The minimum is based on the species' adult size (12 inches (spines)), territorial range, and behavior pattern. Most Long Spine Urchin sold at small juvenile size will reach full adult size within 12-24 months and the system must be sized to the adult, not the juvenile.
The Long Spine Urchin is rated intermediate difficulty on this care sheet. It needs a tank of at least 55 gallons, a temperature of 76-80°F (24-27°C) and pH 8.1-8.4. Adults reach about 12 inches (spines) and live 4-8 years. Long Spine Urchin (Diadema setosum) is a intermediate-care saltwater species that thrives in tanks of 55 gallons or larger with stable parameters.
Long Spine Urchin requires standard reef parameters held tightly stable: Temperature: 76-80°F (24-27°C) Specific gravity: 1.025 (refractometer-measured) pH: 8.1-8.4 Alkalinity: 8-9 dKH Calcium: 420-450 ppm Magnesium: 1300-1400 ppm Ammonia + nitrite: Both 0 ppm Nitrate: Under 10 ppm Copper: 0 (lethal to invertebrates) Long Spine Urchin is sensitive to copper - never medicate the display tank with copper if Long Spine Urchin is present.
Long Spine Urchin is a algae grazer. Provides natural algae control by grazing on filamentous, hair, and turf algae throughout the tank. Supplemental nori sheets and algae wafers ensure adequate nutrition when tank algae is depleted. Avoid copper-based algaecides - they kill Long Spine Urchin. Feed Long Spine Urchin appropriately for its size + activity level.
Long Spine Urchin is generally peaceful and compatible with most reef community species. Avoid keeping with predatory fish that view inverts as food: large wrasses (especially halichoeres + thalassoma), triggerfish, pufferfish, and certain large angelfish. Multiple Long Spine Urchin can share a tank but compete for food. Browse care guides for tankmate-compatibility tables for Long Spine Urchin and similar species.
Long Spine Urchin reaches 12 inches (spines) at adulthood with a captive lifespan of 4-8 years with proper care. Many marine inverts molt periodically; provide adequate calcium and a stable parameter regime to support healthy molts. The minimum is based on the species' adult size (12 inches (spines)), territorial range, and behavior pattern.
Long Spine Urchin is sensitive to copper, ammonia spikes, low oxygen, and rapid parameter swings. NEVER use copper medications in a tank with Long Spine Urchin. Symptoms of stress: reclusive behavior, color loss, refusal to feed, abnormal molting (incomplete or stuck molts). Most Long Spine Urchin deaths trace back to acclimation shock or parameter mismatch - drip-acclimate over 45-60 minutes when adding to a new tank.
Long Spine Urchin (Diadema setosum) is native to Indo-Pacific reef ecosystems, with wild populations distributed across coral reefs, sandy lagoons, and rocky tide pools. Captive specimens are typically wild-collected; some species are starting to be aquacultured but most Long Spine Urchin sold today still comes from wild reef collection. Sustainable sourcing matters - look for vendors who can verify their collection practices, and consider aquacultured alternatives when available.
Other species in the same category with care profiles on Fast Aquatics. Click any name for the full husbandry breakdown.
Long Spine Urchin taxonomy and care recommendations cross-checked against the following authoritative references and our internal vendor + breeder database.
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