How Fast Do Zoanthids Grow?

Have you noticed your Zoanthids growing painfully slow? Or maybe they are taking over your aquarium, and you want to know why…

When it comes to Zoanthid growth, there is no guideline to how fast they will grow. Every aquarium hobbyist is different, which is not a bad thing. What it does mean, is that every hobbyist in the aquarium trade will have a slightly different aquarium setup which can influence the growth rates of your Zoanthid Coral. 

Just like humans, Zoanthids grow at different rates, therefore depending on what type of Zoanthid you choose, it is likely to determine its growth rate. For example, many hobbyists will mention that some species of Zoanthids will grow one head per colony every week, while others may only see one head per month. 

Zoanthid Coral Growth 

Zoanthids (or Zoas for short) are fundamental for structuring coral reefs around the world, and are possibly the most popular type of coral among hobbyists to collect in reef aquariums because of their epic color morphs and easy care level. 

When it comes to Zoanthid growth, what we do know is that Zoanthids are one of the fastest-growing corals in reef aquariums and their growth rate seems to differ between aquariums. 

What you need to understand is that your reef aquarium has a different personality to someone else’s aquarium. Even if you follow the recommended guidelines to keeping Zoanthid Corals and keep everything inside your aquarium stable, don’t be surprised if you get different growth results to other Zoanthid enthusiasts. Just remember, some corals may do better in your aquarium, while some corals may struggle, and that is OK.

As you probably already know, we reef tank hobbyists are a friendly bunch, and many of us are there to help out and share experiences. Some hobbyists have mentioned that Rasta Zoas and Zombie Zoas have a slower growth rate (1 polyp a month) than Dragon Eye and Utter Chaos Zoas (3-5 polyps a month).

One thing we reef hobbyists understand is that when Zoanthids grow, it is almost exponential. For example, if you start with 2 polyp heads and they both successfully reproduce, you will get 4 polyps. If this process is repeated you will get 8, then 16 polyps, and so on. 

However, Zoanthid growth is still not fully understood, therefore more research is needed into species-specific growth rates. So if you are up for the challenge ‘water you waiting for’? Start your own mini research project!

How Does Acclimation & Fragging Affect Zoanthid Growth?

While you may want your Zoanthid to have the fastest growth possible, your Zoa may take a few months before it starts to fit into its new surroundings, this process is known as acclimation. After this process, your Zoa can then fully relax and focus on growing some stunning new heads. 

If your Zoa is an enthusiastic grower, that is great news, especially if you plan on fragging them. Now, if you are new to the wonderful reef-keeping world, fragging simply means removing small parts from the “mother colony” and placing them elsewhere, which is how many of us create mesmerizing Zoa gardens.

However, if you decide not to frag your Zoanthid colony as it goes through rapid growth, it is likely to start dominating your reef aquarium, growing over anything in its path and/or shading out (what we would call “blocking out”) areas of the aquarium. When Zoas start shading other corals, it can stunt their growth or even kill them.

What Affects Zoanthid Growth Rates?

Just like us, your Zoanthid Coral will want to feel comfortable in their home! 

Firstly, your reef aquarium’s maturity plays a part in your Zoa’s growth. Now, I know how exciting it is when your Zoanthid finally arrives, but buckle your seatbelt for a while longer… 

If you are a new reefer, make note that it generally takes around one to two years for a tank to become fully mature with healthy growing corals. So, a little tip from me to you, get your water parameters under control and stable before you start shopping for some epic Zoas, it will be worth the wait, trust me!

Secondly, you can have a mature tank, but the water quality may be all over the place. Fluctuations in water parameters can affect the growth of your Zoanthid, therefore, you want to regularly check the water chemistry requirements for the type of Zoa you have and check levels with a test kit, or drop a sample off at your local fish store for them to analyze. 

You should also consider how light and water flow can influence your Zoa’s growth. Always check how much Photosynthetic Available/Active Radiation (PAR) your Zoanthid coral requires for optimum growth, and also check that the lighting fixture is working properly. Water flow is also important for growth, as it is used to circulate water around your aquarium, and carry waste away from corals. However, if your Zoanthid is placed in a flow area which is too high, its polyps may not open, which can stunt its growth and development. 

And finally, Zoanthids can be a little “fussy” when it comes to things brushing up against them. This could be anything from hair algae, to fish that live inside your aquarium. Anything that could irritate them is likely to make your Zoanthid grow at a slower pace.

All of these factors can dictate how fast your Zoanthid will grow, or if it will even grow at all.

Tips To Growing Zoanthids

So, with so many things that can affect your Zoa’s growth, here are some tips to encourage your Zoanthid to grow to their maximum ability.

These include:

  • Keeping your water parameters stable.
  • Performing regular water changes.
  • Purchasing a PAR meter to monitor the light intensity inside the aquarium. 
  • Regularly feeding your Zoanthid(s) with meaty foods such as Oyster-Feast, 2-3 times a week.
  • Dipping your Zoanthid into a Bayer Dip (Mix 80mL of Bayer with 1/2 gallon of aquarium water) before adding it into the aquarium to avoid aquarium pests, such as zoanthid eating nudibranchs, sea spiders, and sundial snails.
  • Avoiding fish and invertebrates that are known to nip on corals. 
Check out this crazy time lapse of a Zoanthid’s growth


Zoanthid growth is a topic that is not fully understood, and more research is needed into species-specific growth rates. 

However, we do know that Zoanthid growth rates differ between the type of Zoa you have and the aquarium setup you have; the likelihood of you having the same aquarium setup as me, or your reefing buddies, is very slim.

At the end of the day, growing corals is not a race or a competition. As long as your Zoanthid Corals are happy, healthy, and alive, that is all that matters.

Check out our ultimate zoanthid coral care guide for more information!

  • Roy Lee

    I have an unhealthy obsession with reef keeping and maintaining successful tanks. If you haven't noticed from the website, I love everything related to saltwater tanks like coral, fish, and everything else in between.

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