What Are Soft Corals (With Tips To Keep Them Healthy)

When you are a new aquarist, starting a reef tank could feel like a daring task. Especially when you start noticing all the coral species there are. Even if you have a bit of experience, you might not know exactly what soft corals are.

Soft corals are species of coral that do not have a stony external skeleton. Due to this, they are soft, bendable, and resemble plants and trees. Soft corals are different from false corals such as mushrooms and zoanthids. They are also known as non-reef building corals.

There is a huge variety of species of soft corals that can embellish your reef aquarium. Since they are different from other corals, they need particular care. In this post, you will have the insights and the tips, all in one!

What are soft corals: a quick guide

Corals without stony external skeletons are classified as soft. Instead of having a skeleton, soft corals are made of soft and fleshy polyps. In its tissue, there are small stony formations made of calcium carbonate. These formations are known as sclerites.

The sclerites give support to the soft structure of these corals. These small stony formations look like crescent moons and cover all the surface of the soft corals. To the naked eye, they look like corrugations, but they are actually little bone-like formations.

In many cases, soft corals resemble plants due to their bendable characteristics. Some species of soft corals are similar to grass; some others are similar to trees. Soft corals move with the current, making them look like if they danced.

They are great for beginners, as they don’t need extensive care to thrive. Most species of soft coral can adapt well to reef tanks. Soft corals take their nutrients out of the water through absorption, making them practical for starters.

One of their distinctive characteristics is that they prefer dim light. You can place them at the bottom or the top of your tank, depending on the power of your lights.

Without having a calcium carbonate skeleton, soft corals cannot create strong structures. In this sense, these species cannot build reef walls in aquariums. Instead, soft coral species work together to create a balanced ecosystem. 

Recent scientific studies have discovered that soft corals can improve the quality of the environment. They indirectly contribute to the reef-building of hard corals. So, soft corals offer benefits beyond the looks.

It is necessary to understand that corals are living organisms. Placing soft corals in a reef tank can help you create a better ecosystem for your other species. Together, your species of soft corals will create a community.

Soft corals live in colonies, which they establish after finding a safe environment. To move safely, soft corals create a path of toxic compounds. Be careful with the damage these toxins may cause to other species.

Within their colonies, soft corals reproduce asexually through budding. Budding is the process where soft corals create a little copy of themselves. This copy will then establish a new colony.

Soft coral classification

As an added value to this classification of corals, there are plenty of species and varieties you could choose from. Soft coral is the generic name for all the species that do not have skeletons.

Although you don’t need all the taxonomic information for your hobby, understanding that there are many different coral specimens considered soft will help you take better care of them. And besides, there are some stunningly beautiful varieties around. 

Some known soft coral species are the cladiella corals, the discosoma corals, the pachyclavularian corals, and palythoa corals. All these species have potent toxins, so handle them carefully with gloves.

If you want to venture into the world of soft corals, the elaborate colonies and beautiful species will not let you down. They will give your reef aquarium depth in diversity, and you won’t have to do any miracles to keep them alive.

Tips to keep soft coral healthy

Since there are many species classified as soft corals, giving general tips for all of them might be a difficult task. Some species can have some specifications or particular care. The care of some species does not necessarily suffice the needs of others.

However, there are some universal tips to keep your soft coral healthy. 

Water quality

Since most soft corals will be feeding from the water from the reef tank, maintaining good water quality is a must. A pH of around 8.3 would provide the ideal conditions for soft corals. Soft corals also benefit from filtering with the addition of a protein skimmer.

Apart from the pH, salinity and nitrate are also relevant parameters. Try to monitor them regularly to provide the best conditions possible. Regarding water temperature, keep your tank around 78 degrees Fahrenheit.

Since this type of coral is soft, bendy, and moves with the current, the environment needs to allow movement. In this sense, a gravity of about 1.025 would be ideal. To help with water flow, you can use powerheads. Just make sure they are not directly hitting the coral.

 Light

As previously mentioned, soft corals benefit from moderate light. To improve the health of your soft coral, you can aim to 2-3 watts per gallon for about 12-14 hours a day. One trick to help soft coral grow is to gradually increase the quality of the light you use.  

Feeding

Apart from helping your soft corals with light, you will also want to feed them correctly. Remember that corals are animals, and therefore, they need feeding. Luckily, feeding soft coral is not a tiresome duty.

Many soft coral species have zooxanthella, which is a symbiotic dinoflagellate alga. The zooxanthella lives on the polyps of the soft coral, providing it food in exchange for a safe environment to live in. 

Soft corals feed on the zooplankton in the water, so they will be fine as long as there are nutrients in the water. For soft corals that don’t contain zooxanthella, you will need to occasionally feed them. You can use micro food for invertebrates.

One way to spot if a soft coral has zooxanthella is to check if it has a brownish tone on its surface. They will also have brighter colors on their spicules. Having this information will help you better take care of your soft coral.

Protection 

Soft corals are territorial animals. They spread toxic compounds to prevent the growth of other species around their territory. To protect themselves from crustaceans and fish, they have sharp spicules. In most cases, they will be able to defend themselves.

The main risk for soft corals is snails. These animals can make their way inside the coral through the polyps and eat it from the inside out. Try to protect your soft coral from snails, and they will thrive in your aquarium. 

Comparing soft and hard coral

There are several differences between soft and hard coral. Learning how they work and how they distinguish themselves from each other can help you with your aquarium.

Hard coral is divided into SPS, which stands for small polyp stony, and LPS, which stands for large polyp stony. In contrast to soft corals, both these varieties of hard coral have a calcium carbonate skeleton. 

In the table below, you will find a comparison between soft and hard corals.

CriteriaSoft coralsHard corals
  HardnessThis type of coral does not have an outer calcium carbonate skeleton.Hard corals have an outer calcium carbonate, which gives them their hard exterior.
  BuildingSoft coral polyps have an eight-fold symmetry, forming eight tentacles.Hard coral polys have a six-fold symmetry, forming six tentacles.
  Reef-building capacitySoft corals cannot build reef. They live in colonies.Hard corals are building-reef corals. Thanks to their hard exterior, they can create strong structures.
    CareSoft corals benefit from moderate light. With these conditions, they can better grow and reproduce in a reef tank. This makes their care more practical.Hard corals benefit from intense light. The care for these species is more demanding and takes more time.
    ProtectionSoft corals move, spreading toxins on their way. Using their toxins, soft corals can defend themselves from predators.When predators such as fish try to attack hard coral, the polyps retract to the interior of the skeleton.
  FeedingSoft corals feed from the zooplankton of the water. They also feed with the help of zooxanthella.Hard corals have a similar method of feeding. Depending on the species, some corals hunt using their polyps.

As you can see, there are several differences between these two types of coral. In the long run, caring for soft corals is more practical for beginner aquarists. Soft corals don’t need extensive care and can grow quickly.

Soft corals are hardy species that can grow almost anywhere. They have a high tolerance to aquarium conditions, don’t suffer too much from water fluctuations, and don’t need too much light or water flow.

Give them a try and see for yourself!

Bart Sprenkels

I have been keeping multiple aquariums since I was 18 years old. Just like many of you, I started with two goldfish but quickly learned they were not suitable for aquariums. Later, I switched to a tropical community tank and I also have two pet musk-turtles in a bigger aquarium. You can read more about me here.

Recent Posts