Horseshoe crabs are fascinating, ancient marine arthropods often added to reef tanks for their constant movement and sand-sifting behavior. With their dome-shaped shell and long tail spine, they are excellent scavengers that naturally stir the sand bed while searching for food. When properly housed, they can help keep substrate aerated and free of detritus. However, horseshoe crabs have very specific needs and are best suited for large, mature reef systems.
Horse Shoe Crab
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Reef Compatibility: Peaceful and reef-safe; may shift sand or knock over unsecured frags while burrowing
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Tank Size: 125+ gallons (larger strongly recommended)
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Tank Maturity: Well-established reef (6–12+ months)
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Substrate: Fine sand bed, 3–4 inches deep minimum
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Feeding:
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Naturally feeds on worms, microfauna, and detritus in the sand
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Supplemental feeding often required
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Accepts sinking meaty foods (pellets, mysis, clam, chopped seafood)
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Spot feed near the substrate
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Water Parameters:
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Temperature: 72–78°F
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Salinity: 1.023–1.025
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pH: 8.1–8.4
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Nutrients: Low to moderate, stable conditions
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