Harlequin Shrimp

Harlequin Shrimp (Hymenocera picta / Hymenocera elegans): A brilliantly patterned, starfish‑specialist predator and one of the most visually striking invertebrates in the reef hobby. Harlequin shrimp are admired for their beauty, pair‑bonding behavior, and unique feeding ecology—but they require very specific care due to their exclusive diet. ⭐ Identity & Appearance Harlequin shrimp are small (about 5 cm / 2 inches) and cream‑colored with large, vivid spots that range from red/pink with yellow edges (Pacific populations) to brownish with blue edges (Indian Ocean populations). Their flattened claws, leaf‑like antennules, and petal‑shaped sensory organs give them a distinctive, almost ornamental look. 🌍 Natural Habitat They inhabit coral reefs across the tropical Indian and Pacific Oceans, including Hawaii, Indonesia, Australia, Panama, and the Galápagos. They live in pairs, occupying caves and crevices between 1–30 m depth. 🧠 Behavior & Social Structure Harlequin shrimp are monogamous, territorial, and almost always found in pairs. Same‑sex individuals fight aggressively—males may fight to the death. Pairs hunt cooperatively, flipping starfish and consuming them slowly over days or weeks. 🍽️ Diet (Critical Care Requirement) Harlequin shrimp feed exclusively on starfish—they will not eat pellets, frozen foods, or algae. Key points: A mature pair consumes 2–3 medium starfish (6–10 cm) per week. They accept nearly all starfish species, including Asterina, Linckia, Fromia, Protoreaster, and even Crown‑of‑Thorns. They may eat brittle stars if starving. If starfish are unavailable, they will starve—no exceptions. Many aquarists maintain a refugium of Asterina or use chocolate chip starfish as a cost‑effective food source. 🏡 Aquarium Requirements Tank size: 10 gallons for one; 20+ gallons for a pair. Water parameters: Temp: 72–82°F (optimal breeding at 82–89°F) Salinity: 1.023–1.025 pH: 8.0–8.4 KH: 8–12 Nitrate: <20 ppm Flow: Mild—Harlequins are weak swimmers. Copper: Lethal even in trace amounts. Hiding places: Essential—caves, crevices, rubble. 🦐 Molting & Lifespan Harlequin shrimp molt every 18–30 days, depending on age. After molting, they hide until their new exoskeleton hardens. With proper care, they can live up to 7 years in captivity. 🤝 Compatibility Reef-safe: Yes—harmless to corals and fish. Tankmates: Peaceful fish, gobies, blennies, clowns, fire shrimp, snails, small hermits. Avoid: Other shrimp species, large predators, same‑sex Harlequins. 📌 Quick Summary: Size: ~2" Temperament: Territorial; best kept as a bonded pair Reef-safe: Yes Diet: Starfish only Care level: Advanced (due to feeding requirements) Origin: Indo‑Pacific & Central Pacific Key needs: Starfish supply, mild flow, stable parameters, hiding spaces