Knobby Starfish

Geographical Origin and Habitat: Broadly distributed in the tropical Indo-Pacific, from East Africa and the Red Sea to the Western Pacific. Found on sandy bottoms, lagoons, and seagrass meadows.

Taxonomy: Member of the Oreasteridae family. Features a robust body with five thick arms and prominent, hardened knobs or tubercles scattered across its dorsal surface.

Social Behavior: Solitary and predatory. Moves slowly over the substrate using its tube feet, ignoring fast-moving fish but preying on sessile invertebrates.

Coloration and Sexual Dimorphism: Extremely colorful, ranging from brown and grey to vibrant orange, yellow, or red, often with contrasting knobs. No visible external dimorphism.

Tank Setup: Needs a large tank of at least 100 gallons with extensive open sandy areas. Rockwork should be spaced out to allow easy movement of this bulky starfish.

Diet and Feeding: Carnivorous. Requires target feeding by placing pieces of shrimp, clam, or fish flesh directly under its body 2-3 times per week.

Water Quality: Needs stable parameters: temperature 22-28°C, pH 8.1-8.4, SG 1.023-1.025. Perform slow drip acclimation over 2-3 hours when introducing.

Compatibility and Tankmates: Not reef-safe. Will consume soft corals, zoanthids, sponges, clams, and small urchins. Keep only with large, peaceful fish.

Aquarium Breeding: Broadcast spawning. There are no records of successful reproduction or larval rearing in home aquariums.

Risks and Diseases: Intolerant to copper-based treatments. Susceptible to rapid tissue necrosis if subjected to sudden osmotic shock or poor water quality.