Keeping Zoanthids Happy

Just about all hobbyists enjoy collecting Zoanthids and Palythoas. Beginners love the fact that there are so many different types to choose from. Add that to most zoas being very reasonably priced and many varieties are not demanding at all. This makes it easy for beginners to keep zoas happy. Intermediate and advanced hobbyists adore them because of the vibrant colors they can add to an aquascape.

Zoas and palys are the perfect choice for filling in spaces within the rockwork and they help to create that iconic tropical reef aesthetic.

We field a ton of questions about keeping zoas and palys happy in the reef tank. That’s why we decided to pick a few of the most frequently asked zoa questions for this week’s post! In this article, we are going to discuss some of the ways reef keepers can improve their success with zoas. So, let’s dive right in!

The Basics

Since zoas are so closely related to sea anemones, they almost look like smaller versions of sea anemones. One of the differences is that these corals grow in mats of polyps, or colonies, whereas anemones do not. Each zoa polyp develops a distinctly colored crown. They don’t have a skeleton like stony corals, so they are instead classed as soft corals.

Zoas are sometimes confused with Palythoa spp., but zoanthids are generally smaller and more compact than palys. Zoas also tend to be more colorful and have shorter tentacles (lashes) and a rounder mouth. Zoas and Palys are favorites of reef keepers because they have such a wide range of colorations and patterns.

To sum all this up, there is a very wide range of diversity within the genus. To the untrained eye, it is even difficult to tell where Zoanthids stop and Palythoa begin. And we can’t forget protopalythoa and parazoanthids, both of which are commonly kept in reef tanks. Protopalys and parazoas are very hardy and easy for beginners to keep, but we’ll cover more on care requirements below.

Where do zoas grow?

Zoanthid corals can be found in most tropical coral reef ecosystems. They are very common in Indian and Pacific Oceans as well as in the waters of the Atlantic in the Caribbean. Zoas are found in a wide range depths and temperatures along coral reefs in these regions. These corals have adapted to extreme conditions that might surprise some reef keepers.

For example, zoas living along tidal pools have grown accustomed to being out of the water when the tide goes out. These colonies have evolved to coat themselves with a protective slippery coating when exposed to air.

Some species of zoanthids have even been discovered at the depths where it was assumed to be too cold for these corals to grow. However, a species of isozoanthus was identified at depths of 800 meters off the coast of the Azores. Clearly, there is very little sunlight that reaches that depth but even more remarkable is the water temperature is an average of 50-60°F!

Qualities like this are some of the reasons why zoanthids are one of the most successful corals for aquaculture. These types of characteristics can also help when it comes to transportation of corals as well. Zoas and palys have even been known to survive after days of being stuck in transit!

Zoa polyps come in different sizes and shapes based on where they live on the coral reef. They are often found on reef crests and atop rocks in very turbulent areas. Those that live near turbulent water will have shorter polyps and tentacles, smaller oral discs, and form dense, encrusting mats.

In deeper, calmer water, their polyps are elongated, and their tentacles are longer. These zoas have larger oral discs, and they secrete more mucus.

How fast do zoanthids grow?

Some zoas grow and spread much more quickly than others. For example, some types of zoas can grow one or two polyps in a month and spread slowly. However, other varieties can grow five or six polyps at a time and spread like wildfire! It all depends on the water parameters. Specifically, how stable are the parameters? Other factors like the age of the reef tank system, lighting and nutrients also play a huge role in growth rates.

As an aside, the going rate of the zoa variety is the best way to tell how fast they will grow. Typically, the more expensive the polyp, the slower they will grow. Some types of zoas grow very quickly and are on the cheaper end of the price range. Some grow very slowly, so their price stays high on the market.

Also, not all systems are the same. It’s possible for a variety of zoas to thrive in a reef keepers’ system but that same variety may not flourish in the adjacent frag tank. Zoas are hardy, but like all corals, but they do best in a stable environment. If you want zoas to grow faster, the first thing you need to do is keep the water conditions as stable as possible.

If you take good care of your zoanthids, you’ll see them grow. If you provide it the correct conditions, practice good husbandry and are patient, they will grow!

Will zoas grow on sand?

The answer to this question is yes, and no! Zoas are soft corals and are not reef builders so their nature would indicate that they will need to attach to rock or another stony, stable surface where they can be stationary. In nature, they would not typically grow on sand; however, in the reef tank it is possible to have a healthy zoa garden grow on the sand bed. This is especially true for mature systems that have a more solidified sand bed surface.

Zoas can grow on both living and dead surfaces, it is not uncommon to find zoas growing onto an abandoned snail shell that is now home to a hermit crab. Decorator crabs as well as sea urchins have both been home to zoa colonies in the reef tank.

Should you feed zoas?

This is a tricky question to answer. But it truly depends on the reef tank system. A newer reef tank that has not matured will most likely need to feed sparingly to benefit all corals and inverts in the system. Zooxanthellae provides most of the energy that zoas need to survive.

Zoas rely on zooxanthellae to convert light to food. This process is how plants use photosynthesis to convert sunlight to food. Zooxanthellae is a type of photosynthetic algae found in corals and inverts. The zooxanthellae are protected by the coral, and in exchange, the algae provide the coral with oxygen, glucose, amino acids, and other nutrients.

Zoas can also get nutrients from the reef tank systems waste compounds. The water will contain nitrates and solid waste particulates courtesy of the reef fishes that are undoubtedly well fed. So, we can’t say for certain if zoas require feeding, but doing so can improve the overall health, growth, hardiness, and coloration of zoas and all corals.

Do zoas like bright light?

Because zoanthids can live in wide range of depths, they can adapt to a wide range of light levels.

The one rule of thumb is that when acclimating zoas to new or more intense lighting, this needs to occur slowly. And by slowly, we mean a period of weeks! Every two weeks the frag or colony can be moved a little higher or the lighting intensity can be increased – but it is very important not to rush this process!

Zoas do best in medium light, but they also do well in low and high light. It honestly depends on the variety of zoa and the conditions of the reef tank. Since they rely on zooxanthellae for their nutrition, they need to be acclimated more slowly than other corals like LPS.

How do you make zoas happy?

Here are our top three suggestions for happy zoas:

• Stability! Stability! Stability!
• Don’t overfeed the coral, instead feed the fish generously and let them feed the coral.
• Regular water changes (not too frequent and not too large; zoas like a little bit of nitrate and phosphate but no more than 10ppm is a safe level).
• Automated Top-Off (see item number one).

We hope this article has been helpful in answering some of your zoa questions. Please drop a comment below and let us know what your favorite zoas are!