9 Reasons Your Duncan Coral Closed Up And How To Fix Them!

When Duncan coral stays closed up for extended periods, it is often an indicator of an issue with water parameters. Observing the behavior of this coral can serve as an early warning sign, prompting aquarium keepers to examine their tank conditions and make any necessary adjustments.

Factors such as temperature, salinity, water flow, and water chemistry can greatly influence the health and well-being of Duncan coral.

It is crucial for hobbyists to be attentive to their Duncan coral’s behavior and appearance, as recognizing and addressing potential problems early on increases the likelihood of keeping these corals healthy and thriving. By maintaining proper water conditions and promptly addressing any concerns, aquarium enthusiasts can help their duncan coral open up and enjoy the beauty that Duncan coral brings to their aquatic environment.

We hope that this article will be able to help as many of our readers as possible get their duncan coral to thrive by overcoming the various problems that cause result in your duncan coral closing.

An infographic going over a Duncan Coral CARE SHEET

The Importance Of Water Parameters

duncan coral closed up

Maintaining proper water parameters is essential for the health and well-being of Duncan coral. Imbalances in parameters such as pH, salinity, temperature, ammonia, nitrites, nitrates, or phosphates can stress corals, leading them to close up.

Water chemistry plays a significant role in the success of any reef tank, specifically for keeping Duncan corals healthy. We would highly recommend adding a reef tank water test kit to your accessories to monitor all of the important water parameters for your duncan coral.

Here are the more important water parameters and their expected ranges when keeping duncan corals:

  • Temperature: The preferred temperature for Duncan corals is between 75°F and 80°F. Consistency in temperature is essential to avoid stress on corals.
  • Water Flow: Moderate
  • pH: The ideal pH range for a Duncan coral is between 8.1 and 8.4. If the pH is outside of this range, it may lead to difficulties in the coral’s growth and metabolic functions.
  • Salinity: Maintaining stable salinity levels (1.023 – 1.025 specific gravity) is crucial in preventing stress on the coral, as fluctuating or improper salinity can cause issues.
  • Ammonia, Nitrites: It is vital to maintain ammonia and nitrites levels at 0 ppm (parts per million), as high levels of these substances can be toxic to corals.
  • Nitrates: The optimal nitrate level for Duncan corals is between 5 and 10 ppm. Higher levels can contribute to algae growth and stress on the coral.
  • Phosphates: Keeping phosphate levels below 0.03 ppm is beneficial in preventing algae growth and maintaining healthy coral growth.
  • dKH: Alkalinity between 7 and 12 dKH, is crucial
  • Calcium: Duncan corals rely on calcium and alkalinity for their skeletal growth. Maintaining calcium levels between 380 and 450 ppm.
  • Magnesium: 1200 – 1350

Monitoring all these water parameters and maintaining appropriate levels is the key to ensuring the health and growth of your Duncan coral. Regular water testing and adjustment will help prevent your coral from closing up due to stress or imbalance.

Light Requirements

Lighting is an important factor of duncan corals opening

Duncan corals require the appropriate amount of light to thrive and maintain their health. These corals are photosynthetic, which means they rely on specific light spectrums to produce energy for their growth and well-being via their symbiotic relation ship with zooxanthellae.

Providing adequate lighting is crucial to ensure your duncan corals get all of the nutrition they require and do not retract for extended periods.

It is essential to establish a stable day-night cycle for the aquarium. This simulates the natural environment of the coral and contributes to its overall health. The recommended photoperiod for Duncan corals is approximately 8-10 hours of light and 14-16 hours of darkness.

It is important to note that Duncan corals require low to moderate full-spectrum lighting. Exposing them to excessively intense or weak lighting can cause the coral to close up or retract. Adjusting the light intensity and duration according to the needs of the coral will promote healthy growth and compact extension.

Proper lighting is essential for duncan corals

One of the most common methods of lighting for coral reef tanks is the use of T5 fluorescent lights. These lights emit a balanced spectrum of light that is well suited for the needs of Duncan corals. Ensure that the lights are positioned at a comfortable distance from the coral to prevent excess heat or light exposure.

Another option for providing suitable lighting is metal halide (MH) lights. MH lighting produces a more intense and concentrated spectrum of light, which can be highly beneficial for photosynthetic corals. However, these lights tend to generate more heat, so ensuring proper ventilation and circulation is essential to maintain optimal water temperature.

By carefully considering and providing the proper light requirements for Duncan corals, you can ensure their health and longevity in your aquarium.

Poor Water Flow

Poor water flow can be a problem for duncan coral

Duncan corals are known to prefer moderate water flow within their environment. It is crucial for their overall health and ability to thrive. Ensuring the appropriate water movement is essential for keeping them happy and open.

If the water flow is too strong, it can cause discomfort and stress to the Duncan coral, forcing it to close up. On the other hand, if the water flow is too weak, it’s unable to sufficiently remove waste, deliver nutrients, and maintain oxygen levels around the coral. This can also result in the coral closing up to protect itself from the suboptimal conditions.

Moderate water flow is important for duncan corals

To create optimal water flow for your Duncan coral, consider adjusting the placement of powerheads or wavemakers in the aquarium. Ensure the water movement across the coral is moderate and consistent. You can also observe other corals and marine life in the tank for signs of discomfort due to poor water flow.

Regularly monitoring water flow and adjusting it as needed can significantly help prevent Duncan corals from closing up. By maintaining ideal flow conditions, you can ensure this coral species will remain healthy and flourishing in your aquarium.

Aggressive Tank Mates

Aggressive tank mates can cause problems for your duncan coral

Duncan corals, like other corals in reef aquariums, can be affected by the presence of aggressive tank mates. Certain fish, invertebrates, or even other corals can harass Duncan corals, leading them to retract their polyps for protection.

It’s crucial to consider the compatibility of various tank inhabitants to maintain a healthy environment for all species in the aquarium.

Some common aggressive tank mates that could potentially disturb a Duncan coral include some clownfish species, aggressive shrimp, and coral-eating fish. Clownfish, while popular for their attractive appearance and interesting behavior, can become territorial and aggressive towards other tank inhabitants, including corals.

If the clownfish perceives the Duncan coral as a threat or competition, it might repeatedly nip at the coral’s polyps, causing them to retract and close.

Aggressive tank mates can cause your duncan corals to stay closed

As we covered in our article going over the best anemones for clownfish, part of their natural pairing behaviour includes sucking the anemone to build up its immunity. Some clownfish can mistake corals for anemones and suck them trying to build up immunities but causing the corals to close.

Shrimp, particularly mantis and pistol shrimp, might also pose a threat to Duncan corals. These invertebrates are known for their strong claws, which can be used to harm corals, intentionally or unintentionally. When establishing a reef tank, it is best to avoid these aggressive shrimp or provide a separate tank for them.

Coral-eating fish, such as some butterflyfish species, can directly consume or damage the tissue of Duncan corals. Regularly inspecting your tank inhabitants and preventing the introduction of coral-eating fish can help minimize the potential damage to your corals.

Other corals can sting your duncan coral and cause it to close

Moreover, certain corals can be aggressive towards their neighbors. For example, sweeper tentacles, long stinging extensions of corals like torch or star corals, can potentially harm a Duncan coral’s flesh, causing it to close up as a protective response.

Any physical damage or injury to the coral could also make it close up as a protective response. While choosing tank mates, researching their compatibility with corals, particularly Duncan corals, is essential. Preventing contact between aggressive tank mates and delicate corals like the Duncan can help maintain the overall health of your reef aquarium.

Feeding The Duncan Coral

Problems with feeding your duncan coral may cause it to close up

Duncan corals are unique creatures that thrive in a healthy balance of light and nutrients. Though they receive most of their nutrients from their symbiotic relationship with zooxanthellae and they also filter feed.

Active feeding a duncan coral can help fill any gaps in its nutritional profile and get it to open up. Here are some of our favourite foods to offer your duncan coral:

  1. Mysis Shrimp: These small shrimp are a common food for many corals and are usually available frozen.
  2. Brine Shrimp: Another common coral food, either live or frozen. It’s often enriched with extra nutrients.
  3. Chopped Seafood: Finely chopped fish, squid, and other marine meats can be offered as well. Make sure the pieces are small enough for the coral to consume.
  4. Zooplankton: Various zooplanktonic organisms can be fed to Duncan corals, either collected from the ocean or purchased from suppliers.
  5. Coral-specific Prepared Foods: Many brands offer specially formulated coral foods that contain a blend of different ingredients suitable for Duncan corals.
  6. Phytoplankton: Although primarily meat-eaters, they might also benefit from the occasional phytoplankton feeding, which is more geared towards other coral types.
  7. Reef Roids: This is a brand name of coral food that contains a blend of planktons and particulate matter suitable for corals, including Duncans.
  8. Copepods and Rotifers: These tiny crustaceans can also be a good food source for Duncan corals.
  9. Marine Snow: This refers to a mix of organic particles that float in the water, simulating natural detritus. Commercially prepared marine snow can be used as a supplement to the diet.
An infographic going over Food For A Duncan Coral

One of the preferred diets of Duncan corals includes mysis and brine shrimp. These small invertebrates provide the necessary nutrients to keep the coral healthy, vibrant, and open. Mysis shrimp, in particular, are known for their high protein and fatty acid content, which serve as excellent food sources for not just Duncan coral but many other coral species as well.

In order to feed Duncan coral, a technique called spot feeding can be employed.

Spot feeding involves using a small baster or pipette to gently release the food in the water close to the coral. This approach allows the coral to easily consume the mysis or brine shrimp without being disturbed by the water flow or other tank inhabitants. When spot feeding, it is important to provide an adequate amount of food, without overfeeding, as this can cause issues with water quality.

Food sources for a duncan coral

A consistent feeding schedule is also crucial for the health and wellbeing of the Duncan coral. It is typically recommended to feed them at least twice a week. However, depending on the size of the coral and the tank’s overall health, the feeding frequency may need to be adjusted to suit the coral’s needs.

In conclusion, proper feeding of Duncan coral is vital for its growth and overall health. By providing a diet of mysis and brine shrimp through spot feeding and maintaining a sensible feeding schedule, Duncan coral can thrive and exhibit its captivating beauty in any home aquarium.

Disease Or Parasites

Parasites can cause problems with duncan coral

Duncan corals, like other coral species, can sometimes retract their polyps and remain closed up due to disease or parasite infestation. Although these corals are known for their hardiness, they are not immune to infection or pest-related problems. In this section, we shall discuss the potential diseases or parasites that may lead to a Duncan coral closing up and explore possible ways to address these issues.

An infection can cause the coral to retract its polyps, leading to a closed-up appearance. A common sign of infection is the presence of discolored or damaged tissue on the coral’s surface. This discoloration may indicate the presence of bacteria, fungi, or other disease-causing agents. In some cases, the infected tissue may even die and slough off, leaving a visibly damaged area on the coral.

To address infections, aquarists may need to assess water parameters, maintain optimal water quality, and if necessary, administer targeted treatments to address specific pathogens.

Disease Or Parasites can cause problems for duncan corals

Pests can also cause Duncan corals to close up. For example, certain varieties of coral-eating snails, such as the Drupella species, may target Duncan corals. These snails feed on the coral tissue, causing the coral to retract its polyps and close up to protect itself from further damage.

Other potential coral pests include coral flatworms (Amakusaplana spp.), and Red Planaria (e.g., Convolutriloba spp.), which might cause stress to the coral, leading to a lack of polyp expansion. To mitigate pest infestations, aquarists might consider manual removal of visible pests, introducing natural predators to promote a balanced ecosystem, or using chemical treatments.

In conclusion, disease and parasites are potential factors that may cause a Duncan coral to close up. Regularly monitoring water parameters and carefully inspecting the coral for signs of infection or infestation can help prevent and address these issues. It is also essential to maintain optimal tank conditions and employ a proactive approach to tank management in order to ensure the long-term health of the coral.

Acclimation And Care Of Duncan Coral

Acclimitisation of your duncan coral may cause it not to open
“Duncan Coral” by xAquatics is licensed under CC BY 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by/2.0/?ref=openverse.

Duncan coral is a popular choice for saltwater reef aquariums due to its vibrant colors and community-friendly nature. However, proper acclimation and care are crucial for its survival and growth in a new tank environment.

Coral Acclimation: When a Duncan coral is newly added to the tank, it may close up as part of its acclimation process. It takes time for the coral to adjust to the new water conditions, lighting, and flow. Gently introduce the Duncan coral into the aquarium by using the drip acclimation method over an hour or more. This process ensures a smooth adjustment to the tank’s temperature, pH, and salinity.

Coral Care: Providing proper care for Duncan coral is essential for its long-term health and well-being. Here are the key aspects to consider:

  • Water Parameters: Maintain optimal water conditions for the Duncan coral, with a pH between 8.1-8.4, dKH of 7-12, and a specific gravity of 1.023-1.025. Also, monitor calcium and other trace elements, as they are vital for coral sustenance.
  • Lighting: Duncan coral requires moderate lighting to thrive. Ensure that the aquarium lighting levels are appropriate for the coral’s needs and adjust them if necessary.
  • Flow: Duncan coral prefers low to moderate water flow. Providing the right flow helps ensure proper growth, as well as nutrient and waste exchange.
  • Placement: Plan where to place your Duncan coral within the tank, as they tend to grow quickly when well-fed. Make sure there is enough space for the coral to grow and coexist with other species in the aquarium.
  • Feeding: Duncan coral benefits from supplemental feedings of zooplankton and other coral foods like coral pellets and frozen foods. Feed the coral a few times a week to ensure proper growth.

In summary, the acclimation and care (read our duncan coral care guide here) of Duncan coral play a significant role in its successful integration into a saltwater reef aquarium. By attentively managing water parameters, lighting, flow, placement, and feeding, you can help ensure the coral’s long-term health and compatibility with its new environment.


Allelopathy may cause your duncan coral not to open

One common factor that can cause duncan corals to close up is allelopathy which involves chemical interactions other corals in the ecosystem. Placing other corals too close to your duncan coral may result in the other corals stinging your duncan coral resulting in it closing.

We usually recommend that you try to leave at least one inch of space between your duncan corals and your other corals. This should be enough to prevent the other corals from stinging your duncan coral.

Sudden Changes In The Environment

Sudden Changes In the Environment of your duncan coral can cause problems
“Duncan Frag” by coralhaven is licensed under CC BY 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by/2.0/?ref=openverse.

Duncan corals, like any other coral species, are sensitive to sudden changes in their environment. Quick shifts in temperature, salinity, or other water parameters can shock the coral, causing it to close up as a defense mechanism. This reaction helps to protect the coral from potential harm caused by unstable conditions.

One sudden change that can impact Duncan corals is a rapid fluctuation in temperature. Corals thrive in a consistent temperature range, and when it deviates too quickly, it can cause stress and result in the coral closing up. To prevent this, it’s essential to maintain a stable temperature inside the aquarium, closely monitoring it and taking corrective action when necessary.

Another critical factor affecting a Duncan coral’s health is salinity. Sudden changes in salinity can impact the coral’s ability to maintain proper osmotic balance, leading to stress and closure. To avoid disrupting the coral, aquarists should regularly monitor salinity levels and strive to maintain a consistent and appropriate salinity range.

In addition to temperature and salinity, other water parameters like pH, alkalinity, and nitrate levels can also impact the coral’s well-being. Duncan corals are particularly sensitive to high nitrate levels, resulting in them closing up if these levels become too elevated. To ensure the coral stays open, it’s crucial to keep track of water parameters and maintain appropriate levels.

In summary, sudden changes in temperature, salinity, and other water parameters can lead to a closed-up Duncan coral. To prevent this, it is essential to maintain a consistent and stable environment within the aquarium, consistently monitoring these factors and taking corrective action when needed. By doing so, aquarists can ensure the continued health and well-being of their Duncan coral.

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