Duncans

Duncans: Colorful, Beginner-Friendly LPS Corals

Duncans are a favorite large polyp stony (LPS) coral among reef aquarists thanks to their flowing tentacles, bright colors, and forgiving care requirements. Whether you keep a nano reef or a large mixed reef, Duncans can add movement and personality to your aquascape.

What Are Duncans?

Duncans (Duncanopsammia axifuga) are branching LPS corals with fleshy polyps that resemble oversized zoas or small anemones. Each head extends long, swaying tentacles during the day, often in shades of green, teal, purple, or bronze with contrasting centers.

  • Lighting: Moderate PAR (60–150) is ideal.
  • Flow: Low to moderate, random flow that gently moves the tentacles.
  • Placement: Mid to lower rockwork or sand bed, depending on light intensity.
  • Temperament: Generally peaceful and safe with most reef inhabitants.

Tip: Watch for excessive stretching of the polyps. It often indicates the coral is reaching for more light or trying to escape strong flow.

Ideal Water Parameters for Healthy Duncans

Stable parameters matter more than chasing perfect numbers. Aim for consistency within these ranges:

  • Temperature: 24–26°C (75–79°F)
  • Salinity: 1.025–1.026 specific gravity
  • Alkalinity: 8–9.5 dKH
  • Calcium: 400–450 ppm
  • Magnesium: 1300–1400 ppm
  • Nitrate: 5–15 ppm
  • Phosphate: 0.03–0.1 ppm

Duncans tend to prefer slightly “dirtier” water than many SPS corals. Completely stripping nutrients can lead to pale tissue and poor polyp extension.

Feeding and Growth

While Duncans can live on light and dissolved nutrients, targeted feeding supports faster growth and fuller polyp extension.

  • Offer small meaty foods like mysis shrimp, enriched brine, or reef-specific frozen blends.
  • Feed 1–3 times per week, especially in newer or lower-nutrient systems.
  • Turn off pumps during feeding to help the coral capture food.
  • Avoid overfeeding to reduce the risk of nutrient spikes and algae.

Healthy colonies will steadily add new heads over time, especially when alkalinity and calcium remain stable. For more guidance on building a strong foundation for coral health, see our beginner reef tank setup guide.

Placement, Compatibility, and Common Issues

Duncans are generally peaceful, but they still need personal space.

  • Give them room: Leave several centimeters between Duncans and other corals to prevent stings or tissue recession.
  • Avoid direct blasts: Point powerheads away so the tentacles sway gently rather than whip around.
  • Watch for pests: Check for nudibranchs, vermetid snails, or aggressive neighbors that may irritate the tissue.

If your Duncans stay closed for more than a day or two, check for recent changes in lighting, flow, or water chemistry. A slow, steady approach to any adjustments is best. You can also review our LPS coral care basics for troubleshooting tips that apply broadly to similar species.

With moderate light, gentle flow, and stable parameters, Duncans reward reef keepers with vibrant color, constant motion, and steady growth—making them a standout choice for both new and experienced hobbyists.

Ready to expand your collection beyond Duncans? Explore our overview of easy corals for beginners to plan your next addition.