The Duncan coral, Duncanopsammia axifuga, is a striking large polyp stony (LPS) coral known for its large, fleshy polyps that resemble zoanthids or other button polyp species. Sometimes called whisker coral or daisy coral, Duncans have become a staple in the aquarium trade, thanks in part to successful aquaculture efforts that have made them widely available and more affordable in recent years.
Like all LPS corals, Duncans have a calcified stony skeleton and therefore require relatively high concentrations of calcium, magnesium, and hardness, measured as dKH, to stay healthy. These three parameters are closely linked: calcium and alkalinity (dKH) are both used by the coral to build its skeleton, while magnesium helps stabilize both and prevents unwanted precipitation. If one parameter falls out of balance—such as low magnesium causing calcium and alkalinity to precipitate out of solution—you may see stunted growth, tissue loss, or instability in your water chemistry. Watch for early warning signs such as receding tissue, poor polyp extension, or white patches on the skeleton, which may indicate a parameter imbalance.
A quality reef aquarium salt will naturally have a good concentration of these important elements, but you should test your water to monitor these water parameters to ensure your tank stays within a healthy range.
If your tank falls out of the healthy range, you can generally restore the quality of the water by performing water changes or adding reef supplements, like 2-part, if necessary. You can see parts of the exposed skeleton in the image above, where the Duncan coral polyp has died away.
Individual polyp heads will grow out from a central stalk in a bouquet-like arrangement, as can be seen in the image below of a Duncan coral taken at the New England Aquarium, in Boston.
Duncan coral at the New England Aquarium, in Boston, surrounded by aiptasia
Are Duncan corals easy to keep?
Duncan corals are easy to keep in an aquarium because they are hardy and grow well in relatively lower light and water flow areas. They are often one of the first LPS coral types added to a reef tank.
Their hardiness comes from a broad tolerance for a range of water parameters, the ability to recover from minor injuries, and flexible feeding strategies—they can thrive on photosynthesis alone or benefit from supplemental feeding. Duncans also tend to adapt well to changes in lighting and flow, making them forgiving for beginners. However, problems can still occur if their basic needs are not met. Common failure modes include:
- Tissue recession—often from insufficient flow, poor water quality, or parameter imbalances.
- Polyp bailout—where polyps detach from the skeleton, usually due to severe stress or rapid environmental changes.
- Bleaching—loss of color from excessive light or sudden changes in lighting.
- Stunted growth—from chronic underfeeding or low nutrients in ultra-clean tanks.
Early warning signs include receding tissue at the base, polyps remaining tightly closed for extended periods, pale or bleached coloration, or visible skeleton. Addressing these issues early—by adjusting placement, improving water quality, or supplementing feeding—can usually restore health.
Where should Duncan corals be placed?
The ideal placement for Duncan corals is towards the bottom of the tank, even in the sand bed in the lower-light, slower water flow areas of the tank. They do not need high flow.
Placement matters because Duncans are adapted to deepwater, low-current reefs. Too much light can cause bleaching or tissue retraction, while too little light may result in slow growth and pale coloration. Excessive flow can cause polyps to retract or even damage the fleshy tissue, whereas insufficient flow can lead to detritus buildup and tissue recession at the base.
Practical placement tips:
- If polyps are extended and the coral displays good color, placement is likely appropriate.
- If polyps remain closed, tissue recedes, or color fades, try moving the coral to a shadier spot or reducing flow.
- If detritus accumulates around the base, increase gentle flow to keep the area clean.
Observe your Duncan coral’s behavior for a week or two after placement and adjust as needed for optimal health.
Are Duncan corals fast growing?
The Duncan coral is a fast-growing coral species that will grow even more quickly if regularly fed.
Are they aggressive?
Duncan corals are not aggressive. They are peaceful corals that will share the tank space well with other peaceful corals. Since they are fast-growing, be sure to give them ample space to grow so that they do not crowd out neighboring corals.
Unlike some LPS corals, Duncans do not possess long sweeper tentacles or strong stinging cells. However, aggressive corals such as Torch, Hammer, or Galaxea can extend sweeper tentacles or release chemicals (allelopathy) that damage or kill nearby Duncans. Signs of aggression damage include receding tissue, white or burned-looking edges, or sudden polyp retraction. To prevent problems, leave extra space around Duncans—at least several inches from aggressive neighbors—and plan for their future growth to avoid accidental contact as colonies expand.
Can they touch a Torch coral or other aggressive species?
Do not place a Duncan coral somewhere they will be in physical contact with, or even too close to aggressive coral species like the Torch coral. Aggressive corals will injure or destroy this peaceful coral.
Always monitor the spacing as both Duncans and their neighbors grow, and be prepared to move or trim colonies if they begin to encroach on each other’s space.
Do they need to be fed?
These are photosynthetic corals that can provide themselves with all the nutrition needed, but they will grow faster and fuller if they are fed routinely. These large polyp stony corals can take large meaty foods, as long as the fish don’t steal the meal first.
While Duncans can survive on light and dissolved nutrients, supplemental feeding accelerates growth, enhances polyp extension, and can improve coloration. However, overfeeding can lead to nutrient spikes (elevated nitrate or phosphate), algae blooms, or declining water quality. To minimize risks:
- Feed small amounts 1–2 times per week, targeting individual polyps with a pipette or feeding tool.
- Remove uneaten food after 10–15 minutes to prevent decay.
- Watch for signs of overfeeding: persistent algae, cloudy water, or rising nutrients.
- To reduce food theft by fish or shrimp, feed after lights out or distract tankmates with food elsewhere.
Remember, photosynthetic corals like Duncans benefit from feeding but do not require it to survive in most tanks. If your tank is very low in nutrients (“ultra-low nutrient systems”), regular feeding becomes more important to avoid stunted growth or pale coloration.
Duncan corals are a popular reef aquarium species
One of the reasons these are popular corals is that low-to-moderate lighting is all that is required to keep these amazing animals. This is a deepwater species that comes from low-current reefs around Australia and the South China Sea.
They also have symbiotic zooxanthellae and are photosynthetic, but they are also hunters, capable of capturing and eating prey, and will benefit from regular feedings of brine shrimp, mysid shrimp, cyclops, or small pieces of shellfish.
In the center of the large, fleshy polyps is a mouth, where the food items would be ingested and consumed. Target the mouth when directly feeding this coral. A great aquarium tool to target feed the Duncan coral is Julian’s Thing, which is a long pipette, that will allow you to gently drop a meaty morsel right on the mouth.
Duncan coral grows rapidly, especially when fed well, so when you are picking a location in your tank for that new frag you bought, be sure to give them plenty of room to grow into your reef.
Fragging the Duncan coral
The Duncan coral is relatively easy to frag. The short, stony branches can be easily cut with bone shears or a Dremel tool, and then attach the bottom of the stony stalk to a small piece of live rock with cyanoacrylate glue. For more step-by-step instructions about how to frag Large Polyp Stony corals like these and other corals, get the book: How to Frag Corals on Amazon or iTunes today.
Fragging does stress the coral, and it is normal for polyps to remain closed for a day or two after cutting. To minimize risk of infection or tissue loss, consider dipping the frag in an iodine solution or commercial coral dip immediately after cutting. Place new frags in a low-flow, low-light area to recover, and monitor for signs of healing—healthy frags will begin to extend polyps within a few days and show no signs of tissue recession or discoloration. Watch for brown jelly disease, excessive tissue loss, or persistent closed polyps, which may indicate infection or stress. Prompt removal of unhealthy frags and maintaining stable water conditions will improve survival rates.
Do you dip Duncan corals?
You should dip your Duncan corals before adding them to your display tank, to protect from introducing unwanted pests into the tank.
Common pests or hitchhikers found on Duncans include flatworms, nudibranchs, algae, and occasionally small crabs or snails. Effective dips include iodine-based solutions or commercial coral dips specifically formulated for pest removal. During dipping, observe for pests detaching or falling off the coral, and inspect the coral for any remaining eggs or visible organisms. After dipping, monitor the coral for normal polyp extension and healthy tissue; temporary retraction is normal, but prolonged stress may indicate sensitivity to the dip or residual pests.
What kind of coral is a Duncan?
The Duncan coral is a Large Polyp Stony coral with a calcified skeleton and large fleshy polyps.
Other large polyp stony corals
There are many other large polyp stony corals. To learn more, learn how to care for these other popular LPS too:
- Torch coral care
- Acan coral
- Gonipora
- Favia coral
- Hammer coral care
- Elegance coral
- Blastomussa
- Galaxea coral
For more information
For more information like this post, check out:
Or check out this definitive guide about aquarium corals for more information.