Understanding Heterotrophic Coral: Gorgonia & Precautions for Reef Enthusiasts

The vast majority of corals in the aquarium trade are autotrophic. This means they can derive nutrients and energy from their environment. Some corals, like LPS corals, supplement this autotrophic lifestyle by capturing prey. However, there are fewer corals that are truly heterotrophic. Heterotrophic corals require external feeding to obtain nutrients and survive. In captivity, these corals must be fed regularly, or they risk starvation.

What is Heterotrophic Coral?

Heterotrophic corals are striking examples of marine life. The Dendronephthya, known for its neon contrasting polyps and branching tissue, is a soft coral. Tubastrea, a bright orange LPS coral with vivid yellow polyps, is another commonly available heterotrophic coral. While Tubastrea can thrive in captivity, Dendronephthya presents a more significant challenge. Both corals require high water flow, as they originate from deep waters with strong currents. Interestingly, neither seems to react to low light levels; I have seen Tubastrea thrive under simple fluorescent tubes. However, their unique requirements make them less suited for a standard reef tank.

Caring for Tubastrea Coral

Tubastrea is easier to maintain than Dendronephthya. Spot feeding Tubastrea several times a week with Mysis shrimp is usually sufficient. Daily feeding can lead to rapid growth and asexual reproduction through budding. Aquacultured Tubastrea is becoming more available, improving survivability during shipping since they can be fed properly before transport. With careful planning and feeding to avoid waste, Tubastrea can be a colorful addition to the darker areas of your tank. Overall, they are much more forgiving than Carnation Coral.

Challenges with Dendronephthya Coral

Dendronephthya, on the other hand, does not extend its polyps without adequate flow. Once collected, the colony often closes and spends days in transit without food. Upon arrival, many wild-harvested Dendronephthya are shriveled and on the verge of collapse. Reviving them can be challenging, requiring a constant supply of phytoplankton to cloud the tank several times a day. While regular feeding may help the coral thrive, it can also increase your bioload and strain your system.

Exploring Gorgonia Corals

While not technically corals, Gorgonia are sessile invertebrates that anchor themselves to the reef. They have a sturdy backbone-like structure wrapped in soft, sponge-like tissue. Some Gorgonia, like the Purple Sea Whip and the Golden Sea Rod, are photosynthetic and autotrophic. These make great additions to tanks with appropriate lighting and flow rates for SPS corals. Others, like the Deep Sea Gorgonia and my personal favorite, the Blueberry Gorgonian, are entirely heterotrophic. Like heterotrophic corals, Gorgonia need adequate feeding to maintain good health.

Feeding Gorgonia Corals

Gorgonia should be fed very small prey items, such as rotifers or copepods. While these are not as readily available as Mysis shrimp, frozen, refrigerated, and live cultures can be sourced for feeding. Daily feeding is essential, and it’s best to feed several times throughout the day. You can slow or stop the flow during feeding, but be mindful that Gorgonia may close without adequate flow. Use a baster or pipette to create a cloud of food upstream from the Gorgonia. You may even see the Gorgonia filtering the food from the water. Repeat this several times during feeding to ensure most polyps capture food. Monitor waste levels closely, as this passive feeding can lead to significant waste buildup over time.

Precautions When Keeping Heterotrophic Corals

When considering the more challenging heterotrophic corals, careful planning is essential. These corals require regular feeding, which means deeper tanks that are hard to reach may not be ideal. Instead, opt for shallow tanks that allow easy access for feeding. Additionally, due to the high flow rates in their natural habitats, larger powerheads may be necessary to stimulate polyp expansion. However, these turbulent conditions can be too forceful for LPS corals, potentially damaging their flesh.

Feeding heterotrophic corals can lead to increased waste, necessitating more frequent water changes to maintain lower nutrient levels. While they are not as sensitive as Acropora, heterotrophic corals can still be affected by nutrient buildup.

Planning Your Reef Tank

It's crucial to consider these factors before adding heterotrophic corals to your reef tank. The additional waste, flow, or space needed for full expansion may not be accounted for. If adjustments are made, existing corals may not respond well to the changes. Ultimately, deciding whether your tank will focus on heterotrophic corals from the start can simplify maintenance, although some challenges may still arise.

When discussing heterotrophic corals, I often mention Tubastrea, Carnations, and Gorgonia. These corals exemplify the unique qualities of heterotrophic species. However, related corals like Dendrophyllia and Nephthyigorgia share similar care requirements and success rates. If any of these corals appeal to you, be prepared for patience, regular water changes, and the possibility of heartbreak. Otherwise, disappointment may follow.

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