Soft Corals: How to care for soft corals in a saltwater aquarium

Direct answer: Soft corals are a popular choice for saltwater aquariums due to their ease of care and adaptability. They lack a stony skeleton, making them distinct from hard corals, and are often recommended for beginners. However, some species require specific care, so it’s important to research each type before adding them to your tank.

The term soft coral is used broadly and relatively unscientifically to lump a bunch of related and unrelated coral species into a simple bucket, defined primarily by what they are:

• Soft, with the absence of a major stony external skeleton

And what they are not:

• They are not false corals, like the Mushrooms or Zoanthids.

The reason any of this is important and worth reading about is that many of these amazing animals (yes, they are animals), are some of the most popular, readily available, and easiest to care for aquarium corals you will find in this hobby. But the taxonomy and proper categorization only really appeal to taxonomists. We care about caring for them in our reef tanks, so let’s dive in to learn more about how to care for the soft corals in a saltwater aquarium.

What is the difference between soft coral and hard (stony) coral?

Hard corals, like LPS and SPS (which stands for Large Polyp Stony and Small Polyp Stony), have a substantial external skeleton made of calcium carbonate.

Soft corals, by comparison, have very large, soft, fleshy polyps with tiny pieces of calcium carbonate skeleton included in their tissue. These tiny pieces of the skeleton, called sclerites, look like little crescent moons or even fingernail clippings (gross!).

If you look closely, you can sometimes see these sclerites embedded in the tissue of certain corals. Take a look at this carnation soft coral below.

See those white striations in the skin of this carnation soft coral? Those are sclerites, the not-so-stony skeleton typical of a soft coral. They are harder to see when the tissue is not transparent, but they are present in all of them.

Those white lines that look like striations or maybe even worms are actually bony shards made from calcium carbonate, the same material that makes up the stony skeleton of LPS and SPS coral species. The absence of that more formidable stony structure is one of the important characteristics that define this gang of corals, unlike a Gonipora, which has large polyps that look soft, but those polyps originate in a stony skeleton, similar to the Trumpet coral in the middle image below.

What else makes a true soft coral species?

As mentioned above, these colonial animals lack the calcium carbonate skeleton that is present in Large Polyp Stony and Small Polyp Stony corals. But to differentiate them further from the other non-stony sub-classes (Mushrooms and Zoanthids), we have to look at the individual polyps. The true soft corals belong to the Octocorillia sub-class, which is a term used to describe the corals that are radially symmetrical divisible by 8….er…what? Ok, picture an old school clock with numbers from 1-12…roughly speaking that’s radially symmetrical as divided by 12…now imagine that clock only had hours 1-8, evenly spaced around the clock. The polyps of octocorillians have 8 tentacles. Go ahead, count them.

See how each polyp has 8 tentacles on it? That’s why they are classified as Octocorrilians.

Zoanthids, by comparison, belong to the subclass Hexacorallia (radially symmetrical but in six symmetrical parts vs. 8) and have a different body structure than the true soft corals–and Mushroom anemones belong to the Corallimorphia subclass, which represents a group of animals with a district morphology from the rest.

How are Soft Corals different from mushroom corals and zoanthid corals?

Unlike zoanthids and mushroom corals, these are considered to be “true” corals and not colonial anemones or false corals. That doesn’t really mean all that much for the average hobbyist other than to provide some specificity about what we mean when we use the term.

Being true corals, these animals do have some bony elements (sclerites) and they exist as a colony of cooperative polyps that exist as part of a greater structure–compare with zoanthid and mushroom anemones where the comparatively larger polyps are each an individual organism.

Soft coral types

As mentioned earlier in this article, the descriptor, this term is used to categorize a large group of diverse animals.

The most common soft coral types are:

1. Clavularia
2. Pachyclavularia
3. Alcyonium
4. Cladiella
5. Lobophytum
6. Sarcophytum
7. Sinularia
8. Capnella
9. Dendronepthya
10. Nepthea
11. Anthelia
12. Xenia

Soft Coral care

It is a bit tricky (or imprecise) to try and provide care instructions for a grouping of corals as large and diverse as this. But what I will do here is try to focus on the most commonly available varieties.

They are so popular because many of the species are considered beginner corals. What makes a beginner coral? They are hardy, which means they grow well, they are tolerant of aquarium conditions, perhaps a bit forgiving of minor fluctuations in water quality, and only require a moderate amount of light and water flow.

That pretty much describes the cabbage leather, toadstool, devil’s hand, finger leathers, pulsing xenia, Capella, colt corals, and other similar corals. Standard reef aquarium water parameters will grow these corals well.

Chemical warfare (Allelopathy) in soft corals

Soft corals are not just passive tank inhabitants—they actively compete for space using chemical warfare, a process known as allelopathy. Many soft coral species, especially those in the genera Sinularia and Sarcophyton, release chemical compounds (terpenoids and other toxins) into the water. These substances can inhibit or damage neighboring corals, including both other soft corals and hard (stony) corals. In mixed tanks, this can lead to unexplained coral decline, poor polyp extension, or even tissue loss in species placed too close to aggressive soft corals.

Operationally, this means that running activated carbon, performing regular water changes, and providing adequate filtration are important strategies for managing these toxins in mixed coral tanks. Careful placement is also key—avoid placing sensitive stony corals downstream or in direct contact with large soft corals known for strong allelopathic effects.

If you notice sudden decline, lack of polyp extension, or unexplained tissue recession in neighboring corals—especially after adding or moving a large soft coral—allelopathy may be the cause. In smaller tanks or those with limited filtration, these effects can be even more pronounced. While soft corals are hardy and adaptable, their ability to dominate or suppress other species is a trade-off that aquarists must manage, particularly in mixed or densely stocked systems.

How to grow soft coral faster

The key to boosting the growth of your soft coral is to (gradually) increase the quality of light (meaning give it more PAR or a higher value of PAR) and to feed your tank a few times a week. I’ve fed my tanks with rotifers, and baby brine shrimp, (which in turn were fed nutritious phytoplankton, like above), as well as freeze-dried cyclops, Reef Roids, and even just blast thawed frozen foods in the powerheads to make a variety of food sizes available.

Testing and water chemistry

To keep soft corals, you will want to regularly test for nitrates, pH, and salinity. While setting up your tank, you will want to track ammonia and nitrite, in addition to the water parameters listed above. Every now and then you will want to confirm that the temperature is stable, somewhere in the neighborhood of ~78 degrees Fahrenheit and that specific gravity is about 1.025 and pH is hopefully around 8.2.

You shouldn’t have too many problems keeping water parameters around these levels, as long as you use a high-quality salt mix.

Soft corals are generally more tolerant of nutrient-rich conditions than stony corals. They can thrive at nitrate and phosphate levels that would stress or even kill many SPS and LPS corals. This is partly due to their natural habitats, which often include nutrient-rich lagoons and turbid waters. For aquarists, this means that soft corals are less demanding in terms of nutrient export, but it’s still important to avoid letting nutrients get too high, as this can encourage nuisance algae. In mixed tanks, balancing nutrient levels is crucial: too “clean” and soft corals may struggle; too “dirty” and stony corals or algae may suffer. Use protein skimming, refugia, and regular water changes to maintain a healthy balance.

Dosing supplements

You probably won’t have to manage complex dosing of supplements if you want to keep soft corals. If you are having trouble keeping calcium and alkalinity high, your tank may benefit from the addition of a 2-part additive, but for the most part, I have had soft corals for years without any additional dosing. I just do water changes with Instant Ocean.

Feeding

Corals are animals. Animals like to eat. In addition to providing a good source of reef-building aquarium light, you may also want to feed your corals.

While there is a common belief that soft corals do not require food, that is actually a myth and is quite untrue (Borneman 2001).

While the polyps of your average soft coral species might not have stinging nematocysts, or even the same dramatically visible capture-response that you might see in some other SPS coral species, that doesn’t mean they don’t eat.

Cabbage leather corals and some others have polyps that are capable of capturing and ingesting prey. If the corals you have capture prey, it’s typically a good thing to feed them. A stand-out exception to this rule is with the non-photosynthetic soft corals, like the carnation, which is actually incapable of sustaining itself with photosynthesis.

These corals require regular feeding to survive and are actually not recommended for the beginner aquarist. The key to feeding any coral species is to provide it with food that is the right particle size. Many soft coral species will absorb nutrients right from the water, and others may feed on nanoplankton or bacterioplankton.

If the feeding habits of the coral you’re interested in are not well described, I encourage you to try different feeding regimens and share your results (here or with others).

Check out this comparison between Julian’s Thing and the Sea Squirt to see which tool is best for spot feeding your corals.

Fragging

Fragging soft corals is a fairly straightforward exercise. You want to cut off a piece and attach it to a piece of live rock or a frag plug. If you are trying to frag one of the encrusting species (like green star polyps), creating soft coral frags is even easier, because the GSP will just encrust any adjacent rock in reach. All you will need to do is separate the new rock colony from the parent.

Cutting soft corals is easy, you just use a razor blade or a sharp set of scissors.

However, soft corals often produce copious amounts of slime and may release toxins when cut, which can irritate your skin and potentially harm other tank inhabitants if not managed properly. It’s best to wear gloves and perform fragging in a separate container of tank water, rather than in the main display. After cutting, rinse the frags in clean saltwater before returning them to your tank. Some aquarists use an iodine dip to help prevent infection and reduce stress. Watch for signs of frag stress, such as excessive slime, tissue recession, or lack of attachment, and remove any frags that appear to be deteriorating.

How to attach frags to live rock

Attaching leather can be challenging because they typically are not able to be glued into place. Soft corals are slippery, slimy, and (believe it or not) wiggly. Since many of these fleshy animals are escape artists of the aquarium world, you can use any of the following methods to attach them to live rock (or a plug):

• Plastic container and mesh
• Rubber band
• Toothpick method

The rubber band method (left) and toothpick method (right) are two great ways of attaching slimy, slippery soft corals to an irregularly shaped substrate like live rock rubble.

You can find step-by-step instructions for all of these in the book, How to Frag Corals.

Where to buy

The best value for the money can usually be found by buying frags from a fellow hobbyist in your area. Many of the species commonly kept in the hobby can be fragged easily. So your best bet at getting a hardy, inexpensive specimen that is used to living in an aquarium is to get a piece that is doing well in someone else’s aquarium.

After that, the next best option is to get an aquacultured specimen online or at your local fish store. The term “aquacultured” means that the coral was grown (farmed) in captivity and is also likely to adjust better to aquarium conditions in your home than a wild-caught one.

How to care for each of the most popular types

To learn more about how to care for each of the most popular soft coral types, check out these individual pages:

• Green star polyps
• Devil’s hand
• Toadstool coral or Mushroom leather
• Cabbage leather
• Kenya tree coral
• Pulsing xenia
• Clove polyps

Are soft corals good for beginners?

Several of the most popular soft coral types are strongly recommended as the best options for beginners because they are hardy, easy to care for, and don’t require intense lighting or special feedings.

Can you mix soft and hard corals?

Mixing soft and hard corals can be successfully managed by most aquarium owners, provided that each respective colony is placed in the appropriate location in the tank. Generally speaking, soft and hard corals will have different requirements for lighting and water flow, so when soft and hard corals are mixed, they tend to occupy different spaces in the aquarium.

How to Choose Soft Corals for Your Aquarium

When selecting soft corals for your aquarium, consider the following factors:

• Lighting: Most soft corals require moderate lighting. Ensure your tank lighting meets the needs of the specific coral species you choose.
• Water Flow: Soft corals generally prefer moderate water flow. Too much flow can damage their delicate structures, while too little can hinder their growth.
• Compatibility: Consider the compatibility of soft corals with other tank inhabitants. Some corals may release toxins that can harm other species.
• Space: Ensure you have enough space in your tank for the corals to grow and expand. Overcrowding can lead to competition for resources.
• Growth Habits: Research the mature size and growth patterns of each soft coral species. Some, like Xenia and Green Star Polyps, can spread rapidly and overgrow other corals or rockwork. Plan for future space needs and avoid overstocking with fast-growing species. To contain aggressive spreaders, consider placing them on isolated rocks or in areas where their growth can be easily managed with regular pruning.

Best stocking approach

A thoughtful stocking approach is crucial for maintaining a healthy and balanced aquarium. Here are some tips:

• Start Slowly: Introduce corals gradually to allow your tank to adjust to the new additions.
• Monitor Water Parameters: Regularly test water parameters to ensure they remain within the optimal range for soft corals.
• Observe Behavior: Keep an eye on the behavior of your corals and other tank inhabitants. Look for signs of stress or aggression.
• Adjust as Needed: Be prepared to make adjustments to lighting, water flow, and placement as your corals grow and change.

Sample stocking plans

Here are a few sample stocking plans for a beginner-friendly soft coral aquarium:

Plan 1: Low-Light Soft Coral Tank

• Green Star Polyps
• Toadstool Coral
• Kenya Tree Coral
• Pulsing Xenia

Plan 2: Mixed Soft Coral Tank

• Clove Polyps
• Devil’s Hand Coral
• Cabbage Leather Coral
• Sinularia

Common mistakes

Avoid these common mistakes when caring for soft corals:

• Overfeeding: While feeding is important, overfeeding can lead to poor water quality and algae growth.
• Improper Lighting: Ensure your lighting setup matches the needs of your specific coral species.
• Neglecting Water Changes: Regular water changes are essential for maintaining water quality and coral health.
• Ignoring Compatibility: Research compatibility between different coral species and other tank inhabitants to prevent conflicts.
• Unchecked Overgrowth: Fast-growing soft corals like Xenia and Green Star Polyps can quickly overrun a tank, smothering other corals and covering rockwork. Regular pruning and strategic placement are needed to prevent them from taking over.
• Allelopathic Suppression: Failing to recognize chemical warfare (allelopathy) as a cause of poor coral health can lead to mysterious declines in neighboring corals. Monitor for signs of allelopathic effects and use activated carbon and water changes to help mitigate risks.
• Misinterpreting Polyp Retraction: Polyp retraction is often a normal response to stress, water changes, or handling—not always a sign of death. Give corals time to recover before taking drastic action.
• Neglecting Quarantine: Not quarantining new soft corals can introduce pests or pathogens to your display tank. Quarantine new additions to reduce risk.

Final recommendation

Soft corals are an excellent choice for both beginner and experienced aquarists. Their vibrant colors and unique shapes add beauty and diversity to any saltwater aquarium. By understanding their care requirements and avoiding common mistakes, you can create a thriving and visually stunning reef environment. Remember to research each species thoroughly and tailor your tank setup to meet their specific needs. Happy reefing!

References

Borneman, Eric H. Aquarium Corals. Microcosm Ltd; 1st Printing Edition (March 1, 2001)

Ulrich III, Albert B. How to Frag Corals: Step-by-step guide to coral propagation and filling your frag tank with thriving polyps. www.SaltwaterAquariumBlog.com (January 20, 2015).

Ulrich III, Albert B. The New Saltwater Aquarium Guide. www.SaltwaterAquariumBlog.com (April 8, 2014)