Zoanthid Coral Care Guide
Overview
Scientific name: Zoanthus spp., Palythoa spp.
Common names: Zoas, Button Polyps, Colony Polyps
Difficulty: Easy to Moderate
Temperament: Peaceful
Growth rate: Fast (under good conditions)
Placement: Lower to middle areas of the tank, depending on light intensity
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Lighting
Type: Moderate to high light
PAR range: 100–250
Zoas adapt to a wide range of lighting.
Under lower light, colors may appear more brown or dull.
Under higher light, they often display more vibrant fluorescence.
Tip: Start them low in the tank and gradually move up to prevent bleaching.
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Water Flow
Flow: Moderate to strong, random flow preferred
Too little flow = detritus buildup and possible bacterial issues
Too much flow = polyps may stay closed or retract frequently
Aim for a gentle sway of the polyps
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Water Parameters
Parameter Ideal Range
Temperature 76–80°F (24–27°C)
Salinity 1.024–1.026 SG
pH 8.1–8.4
Alkalinity 8–11 dKH
Calcium 400–450 ppm
Magnesium 1250–1350 ppm
Nitrates <10 ppm
Phosphates <0.03 ppm
Stable, clean water is crucial. Zoas tolerate some nutrients but can melt in poor conditions.
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Feeding
Primary nutrition: Photosynthetic (via zooxanthellae)
Supplemental feeding (optional):
Target feed with phytoplankton, reef roids, or powdered coral foods
Helps accelerate growth and color vibrancy
Feed 1–2 times per week if desired
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Placement & Compatibility
Place Zoas on islands or isolated rocks to prevent overgrowth—they spread quickly.
They coexist well with most other soft and LPS corals.
Avoid direct contact with aggressive corals like Euphyllia (torches, hammers).
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Special Cautions
Palytoxin warning: Some Palythoa and Zoanthus species can produce palytoxin, a potent toxin dangerous to humans and pets.
Wear gloves and eye protection when handling.
Never scrub, boil, or frag them in enclosed spaces.
Melting Zoas: Often caused by:
Unstable parameters
Pests (nudibranchs, sundial snails, zoa spiders)
Bacterial infections
Low flow or excess detritus
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Pests & Diseases
Watch out for:
Zoa-eating nudibranchs (look like tiny white slugs)
Sundial snails
Zoa spiders
Asterina starfish (some species may eat Zoas)
Use coral dips (e.g., iodine-based or Revive/Reef Dip) before adding new colonies.
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Propagation
Method: Fragging (cutting or chipping off polyps)
Best tool: Coral scalpel or bone cutters
Glue or epoxy the frag to a new plug or rock
They’ll spread and encrust rapidly under stable conditions
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Signs of Health
Open, full polyps
Vibrant coloration
Regular new polyp growth
Closed, shrinking, or melting colonies = check water parameters, pests, or lighting
