Duncan Coral

Overview

General Description: Duncan Coral is a branching LPS with fleshy, flower-like polyps extending from tubular corallites. It is popular for visible feeding responses, moderate care requirements, and readily produced daughter heads.

Appearance: Each round polyp has a central mouth surrounded by long tapered tentacles. When expanded, the tissue can hide much of the branching skeleton.

Notable Characteristics: Large daily polyp expansion, strong feeding response, visible branching growth, relatively mild aggression, and good tolerance compared with many LPS corals.

Natural Habitat

Native Distribution: Recorded primarily from Australian waters and adjacent western Pacific regions.

Natural Reef Habitat: Protected reef slopes, sandy or rubble areas near hard substrate, and deeper or turbid reef environments.

Depth: Often found in deeper or lower-light reef zones, though exact depth varies by location.

Natural Lighting: Low to moderate natural light, frequently reduced by depth or turbidity.

Natural Flow: Gentle to moderate water movement that delivers plankton without battering expanded tissue.

Other Habitat Notes: Colonies may occur where suspended food is available and sediment does not remain on the polyps.

Aquarium Placement

Recommended Placement: Lower to middle rockwork or a stable ledge with low-to-moderate indirect flow and room above and around the colony.

Space Requirements: Allow at least 3-6 inches from nearby corals and enough vertical room for the polyps to expand fully.

Rock/Sand Placement: Secure the skeleton to stable rock. Sand placement is acceptable only if the colony cannot tip, become buried, or abrade its tissue.

Attachment Method: Use cyanoacrylate gel or reef-safe epoxy on exposed dead skeleton or the frag plug; never cover living tissue.

Orientation: Keep corallites upright or gently angled so food and debris do not collect in the mouths and tissue does not rub rock.

Distance From Other Corals: Typically 3-6 inches, with greater distance from aggressive LPS corals with long sweepers.

Other Placement Notes: Account for expansion before choosing a crevice. Tissue rubbing against sharp rock can lead to recession.

Lighting

Lighting Requirement: Low to moderate; strong light is unnecessary and can cause retraction or bleaching without acclimation.

PAR Range: Approximately 50-150 PAR; start around 75-125 PAR and adjust gradually to extension and coloration.

Spectrum Considerations: A balanced reef spectrum with blue and violet wavelengths supports photosynthesis and fluorescence.

Acclimation Requirements: Begin in lower light and increase exposure over one to several weeks after shipping or a major fixture change.

Signs of Too Much Light: Persistent retraction, pale or washed color, bleaching, shortened extension, or tissue recession on the light-facing side.

Signs of Too Little Light: Dull or browned coloration, stretching, weak skeletal growth, and reduced budding despite otherwise suitable conditions.

Water Flow

Flow Requirement: Low to moderate indirect flow that gently moves the tentacles and keeps debris suspended.

Preferred Flow Pattern: Broad, random, or alternating movement rather than a constant direct jet.

Signs of Excessive Flow: Tentacles remain pinned to one side, polyps cannot open, tissue pulls against the skeleton, or recession develops.

Signs of Insufficient Flow: Detritus and mucus collect between heads, food remains on tissue, or extension and gas exchange decline.

Water Parameters

Temperature: 75-80°F (24-27°C)

Salinity: 1.024-1.026 specific gravity (about 32-35 ppt)

pH: 8.1-8.4

Alkalinity: 8-11 dKH, maintained consistently

Calcium: 400-450 ppm

Magnesium: 1250-1400 ppm

Nitrate: Approximately 2-15 ppm; avoid both abrupt nutrient starvation and chronically excessive levels

Phosphate: Approximately 0.03-0.10 ppm; stable measurable phosphate is often preferable to zero

Other Relevant Parameters: Ammonia and nitrite should remain at 0 ppm. Maintain good gas exchange and appropriate potassium and trace elements through regular saltwater maintenance rather than blind dosing.

Parameter Sensitivity: Moderately tolerant, but sudden changes in salinity, temperature, alkalinity, light, or nutrients can trigger prolonged retraction or tissue loss.

Stability Requirements: Stable alkalinity and salinity are especially important for skeletal growth; make corrections gradually.

Feeding & Nutrition

Photosynthetic: Yes. Symbiotic dinoflagellates provide much of its energy under suitable lighting.

Natural Feeding: Captures zooplankton, suspended organic particles, and small prey with its tentacles.

Target Feeding: Optional but beneficial. Place a small portion near each open mouth with flow reduced briefly and remove uneaten food.

Recommended Foods: Mysis shrimp, enriched brine shrimp, copepods, finely chopped marine flesh, and appropriately sized sinking coral foods.

Feeding Frequency: Once or twice weekly is sufficient for most colonies; avoid feeding oversized pieces or every day.

Benefits of Feeding: Can support faster budding, fuller tissue, recovery, and growth in lower-light or nutrient-poor systems.

Special Nutritional Requirements: No special supplement beyond stable calcium, alkalinity, magnesium, balanced nutrients, and appropriately sized food when target feeding.

Growth

Growth Rate: Moderate, with faster head production possible under stable chemistry and regular modest feeding.

Growth Pattern: New daughter heads bud from the sides or base of existing corallites, gradually forming a branching colony.

Maximum Colony Size: Can develop into a large multiheaded colony over several years; practical size depends on available space and fragging.

Space Requirements: Leave room for branches, full polyp inflation, and access for cleaning or fragging.

Overgrowth Concerns: It does not normally encrust aggressively, but an expanding colony can shade neighbors or press tissue against nearby rock and corals.

Aggression

Aggression Level: Low to moderate for an LPS coral.

Sweeper Tentacles: Usually absent or short compared with many aggressive LPS corals; normal tentacles can still sting on contact.

Chemical Warfare: Limited compared with many soft corals, but mucus and dissolved compounds contribute to mixed-reef competition; carbon and water changes can help.

Stinging Ability: Mild to moderate on direct contact and generally limited to the reach of expanded polyps.

Required Spacing: Provide 3-6 inches and additional distance from corals with long sweeper tentacles.

Corals to Avoid Nearby: Keep beyond reach of Euphyllia, Galaxea, bubble corals, chalices, and other strongly stinging LPS corals.

Compatibility

Fish Compatibility: Compatible with most reef-safe fish; butterflyfish, large angelfish, filefish, and other coral pickers may nip fleshy polyps.

Invertebrate Compatibility: Generally compatible with reef-safe shrimp, snails, and crabs, though animals that steal food or walk repeatedly over the colony can irritate it.

Coral Compatibility: Works well in mixed reefs when spacing prevents direct contact and aggressive neighbors cannot reach it.

Potential Predators: Coral-nipping fish, some nudibranchs, and other LPS predators may consume or damage tissue.

Potential Irritants: Vermetid mucus, sediment, food-stealing shrimp, crabs, algae at the skeleton-tissue boundary, and nearby stinging corals.

Fragging & Propagation

Difficulty: Moderate

Propagation Method: Separate one or more healthy heads by cutting the branching skeleton well below the living tissue.

Tools/Method: Use gloves, eye protection, coral bone cutters or a rotary tool, a separate container of aquarium water, and cyanoacrylate gel for mounting. Keep heat, vibration, and debris away from living tissue.

Healing: Return the frag to stable water with moderate light and gentle flow. Polyps may reopen within days, while the cut skeleton takes longer to stabilize and grow.

Special Risks: Cutting too close to tissue can tear the polyp, expose skeleton, or start infection; branching skeleton can splinter sharply.

Safety Considerations: Wear waterproof gloves, eye protection, and respiratory protection when power-cutting dry or aerosol-producing skeleton. Control dust and splashes, disinfect tools, and never cut through inflated living tissue.

Health & Common Problems

Tissue Recession: Often follows unstable alkalinity or salinity, physical injury, excessive flow, a neighboring sting, infection, or chronic nutrient imbalance.

Bleaching: Usually linked to excessive light, overheating, or rapid environmental change. Reduce stress gradually and stabilize the system.

Polyp Retraction: Brief closure after maintenance or feeding is normal. Persistent retraction suggests flow, lighting, chemistry, pests, irritation, or disease.

Pests: Flatworms, nudibranchs, algae, vermetid snails, and other hitchhikers may irritate tissue; inspect, dip appropriately, and quarantine new colonies.

Diseases: Bacterial tissue loss and brown-jelly-like infections can occur after injury or stress and may spread rapidly among heads.

Signs of Stress: Persistent closure, gaping mouths, deflated or peeling tissue, exposed skeleton, brown mucus, bleaching, poor feeding response, or rapid head loss.

Common Keeper Mistakes: Using excessive light or direct flow, allowing tissue to rub rock, feeding oversized food, making abrupt alkalinity changes, and ignoring early tissue recession.

Recovery Considerations: Correct the cause gradually, improve gentle flow, remove trapped debris, separate clearly healthy heads if tissue loss spreads, and quarantine or treat suspected infection promptly.

Beginner Suitability

Beginner Friendly: Yes, for a cycled and stable reef aquarium.

Why: It tolerates moderate conditions, feeds readily, lacks long aggressive sweepers, and gives clear visual feedback through polyp extension.

Major Challenges: Maintaining stable alkalinity and salinity, avoiding excessive flow, recognizing tissue recession early, and preventing food theft.

Before You Buy

Important Considerations: Choose a colony with inflated polyps, intact tissue around each skeleton rim, no brown mucus, no exposed recent recession, and no visible pests.

Space: Allow room for full extension and future daughter heads rather than sizing the location to the contracted frag.

Lighting: Ask about the seller's PAR or placement and acclimate gradually to your system.

Flow: Choose broad low-to-moderate flow that moves tentacles without pinning them.

Aggression: Duncans are relatively peaceful, but must be protected from stronger neighboring stingers.

Parameter Stability: Add only after the aquarium can maintain stable salinity, temperature, calcium, magnesium, and alkalinity.

Long-Term Growth: Plan for a branching multiheaded colony and future fragging access.

Species-Specific Information

Anything important that does not fit above: Duncan Coral was once reported as uncommon in the wild despite becoming widely propagated in aquariums. Individual morphs differ in tentacle length, color, head size, and growth rate. A closed colony is not automatically starving; repeated feeding will not solve unsuitable flow, light, chemistry, or tissue disease.