Why Are My Mushroom Corals Splitting?

Congratulations! Your mushroom is splitting which means you are soon going to be the owner of two mushroom corals, and guess what, mushrooms don’t stop there!

Mushroom corals are relatively fast growers because they are very good at multiplying, either by splitting and dividing themselves into two like a cell or when they move around the aquarium, leaving small parts behind, a process known as ‘pedal laceration’. 

So, if your mushroom coral is splitting, it is no cause for concern, and I am here to tell you everything you need to know about the process in this article. 

Why Do Mushroom Corals Split?

When your mushroom coral starts splitting, it is an epic process. This process is called coral fission, which is very common in Fungiidae corals, like your mushroom. 

The splitting process occurs during the early developmental stages when they are ready to reproduce

How Do Mushroom Corals Split?

When your mushroom corals start splitting, it will usually happen right down the center, through your mushroom coral’s mouth. During this time you may also notice your mushroom coral shrinking, but do not panic as this is normal. Once your mushroom coral has successfully split, it will look nice and fat after about 3-4 days. 

How Long Does It Take For Mushroom Corals To Split?

As your mushroom coral splits, its mouth will get bigger and bigger, until it separates into two individual corals. This usually takes a day or two, however, it depends on your mushroom coral. Some hobbyists have experienced mushroom corals splitting over a week, sometimes even longer. 

White Stringy Material When My Mushroom Coral Is Splitting

When your mushroom coral splits you may see some white stringy material, this is your coral’s mesenterial filaments trying to spill out. 

Mesenterial filaments are the internal folds of tissue that create your mushroom coral’s polyp structure. They are usually white and packed with stinging cells called nematocysts. Therefore, if you notice your mushroom coral ‘spilling its guts’, do not touch them.

Mesenterial filaments spill for three reasons:

  • They are fighting with another coral.
  • They are aggressively eating. 
  • They are stressed.

Splitting is a stressful time for a coral, imagine if you were cloning your body and had to tear your body in half, a few of your tissues may become exposed! However, if your mushroom coral spills its mesenterial filaments, it is nothing to worry about, this is just your mushroom coral’s response to splitting. 

What To Do When Mushroom Corals Split?

When your mushroom coral is splitting, there is not much you can do, apart from being patient and keeping everything inside the aquarium stable. 

How To Create A Stable Environment?

  • Low water flow.
  • Low light (PAR 50-150*).
  • Performing 5-10% water changes every 1-2 weeks.
  • Maintaining the following water levels: Temperature: 76° – 82 °F, pH: 8.1 – 8.4, salinity: 1.023 – 1.025, alkalinity: 9 – 11 dKH, nitrates: <10 ppm, phosphates: <10 ppm, calcium: 350 – 450 ppm, magnesium: 1250 – 1350.

*Some mushroom corals can tolerate more intense lighting conditions, therefore, always check the specific light requirements for the mushroom coral you have. 

You can also target feed your mushroom coral during this time to give it more strength and boost recovery from splitting. Something meaty like phytoplankton, brine shrimp or mysis shrimp is perfect!

How To Know If A Mushroom Coral Is Splitting Or Dying

A splitting mushroom coral will have a clean seam down the middle with healthy-looking tissues (remember that expelling the mesenterial filaments is normal), whereas a dying mushroom coral will look a little worse for wear. If your mushroom coral is dying, it will lose its beautiful coloration and become mushy. Usually, the polyps will be deflated for a long time and may even start turning white

How To Manually Split Your Mushroom Coral 

If your mushroom coral has not started splitting, and you want to encourage reproduction, you can manually split your mushroom coral, which is also known as ‘fragging’.

How To Frag A Mushroom Coral

  1. Firstly, select the mushroom coral you wish to split/frag and remove it from the aquarium. As mushroom corals are similar to urchins, they can squirt liquid, therefore grab some safety glasses or goggles for protection. 
  1. Taking your scalpel, razor blade, or sharp knife, split your mushroom coral in half, straight down the middle, directly through its mouth. 
  1. The next stage can be a little tricky. Next, you need to encourage your mushroom coral to attach to a rock/some rubble and heal. The easiest way is to place your cut mushroom fragments inside a container with some aquarium water and rubble. 
  1. Leave them in the container for a few days to attach and feed them some meaty treats to boost their immune system.
  1. Once they are attached, place them back inside your aquarium. I recommend placing some netting over them to prevent any fish from nipping or laying on your mushroom coral. 
  1. With your mushroom corals attached, you can now move them to wherever you desire, but remember that they may move if the conditions are not quite right. 


A mushroom coral splitting is no cause for concern. If your mushroom coral starts splitting down the center of its mouth, it is naturally reproducing, and soon you will be gifted with two individual mushrooms! 

Keep the conditions stable and be patient during this process as it can be a very stressful time for a coral, but the result is totally worth the wait, trust me! 

Check out our guide for more mushroom coral care 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.

    http://reeftankadvisor.com reeftankroy@gmail.com Lee Roy

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