Why Is My Mushroom Coral Turning White?

Have you just walked up to your aquarium and noticed your mushroom coral turning white?

Corals have a pretty tough life in the wild – the constant battle with changing water conditions and human stressors such as dynamite fishing and destructive infrastructure. While your coral is not going to be blown up inside your aquarium, the natural factors that affect a corals’ life also apply to corals in captivity. 

So, if one or more of your mushroom corals has started turning white, do not panic yet, I am here to tell you why this may have happened and what you can do.

Why Do Mushroom Corals Turn White?

Mushroom corals do not wake up one day and decide to turn white. If your mushroom coral is turning white, it is a sign that something is not quite right in your aquarium. 

1. Transportation Shock

Transportation is a stressful time for corals, and sometimes, corals will not survive very long journeys. If you have opened the packaging and your mushroom coral is completely white, call the local fish store (LFS) or the person you bought it from – most of the time they will give you a refund or send you a new one.

2. Skipping Acclimation

When your mushroom coral arrives, it is a very exciting time, but hang in there for a minute, there are a few things you need to consider before you go ahead and place it inside your aquarium. 

First, you should dip your coral in a coral-safe dip like CoralRX to remove any pests. Mushroom corals are known to carry little hitchhikers from point A to point B. These unwanted pests include several species of flatworms, some copepods/isopods, and nudibranchs/sea slugs. Pests like these will strip your mushroom coral’s tissues and therefore, dipping is a must!

Ok, so you have dipped your mushroom coral, and now you are ready to place it inside your aquarium. Newly added corals should be placed lower down in your aquarium. This gives your mushroom coral time to acclimate to its new water conditions and adjust to your aquarium’s lighting. 

3. Too Much Light

This, or too little light, seems to be the most common reason for mushroom corals turning white. 

If your aquarium temperature is too high or your lighting is too intense, your mushroom coral will expel the symbiotic algae that live in their tissues, called zooxanthellae. Elevated temperatures and intense lighting can bleach your mushroom coral and turn it white. 

If your mushroom coral is being bleached, turn down your aquarium lighting very slowly and move them to a shaded area or lower down your aquascape and monitor them. Any changes you make must be done very slowly to reduce any further stress. 

Mushroom corals are not demanding when it comes to lighting; mushroom corals require low to medium lighting, with a PAR range between 50 and 150. However, some mushroom corals can tolerate higher PAR levels, so always check which type of mushroom coral you have.

4. Too Little Light

Usually, mushroom corals will move if they are not receiving enough lighting in your aquarium, in fact, they are quite unpredictable. One day they are where you left them, and then they have gone and moved somewhere else! This is nothing to be concerned about unless they have moved too close to your aquarium’s lighting fixture. 

However, if they remain in shaded areas for a long period, they may start turning white because the zooxanthellae will not receive enough lighting to perform photosynthesis. In response, the zooxanthellae will expel from your mushroom coral’s tissues, turning your coral ghostly white. This is because the zooxanthellae provide your mushroom coral with pigmentation. 

5. Swings In Water Parameters

Large fluctuations, particularly in salinity, alkalinity, and temperature, can make corals turn white from stress. 

Ideal water parameters for mushroom corals:

  • 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

Keeping the above water conditions will prevent your mushroom coral from turning white. Stability is key in aquariums, even with more forgiving corals like mushrooms. 

It is important to keep on top of your water changes and use RO (reverse osmosis) water. Dosing your aquarium water with water treatments such as AmQuel+ is also recommended. AmQuel is amazing at removing ammonia, chlorine, and chloramines that are often found in tap water, and are toxic to corals and fish. 

6. Slow/Rapid Tissue Necrosis

Take a close look at your mushroom coral. Do you notice algae growth on top of the white areas?

Algae grow on unhealthy, dying tissue, so, if this is the case, your mushroom coral is likely suffering from S/RTN.

If you suspect your mushroom coral has STN or RTN, then you must test the water immediately and check the parameters are within range. If the necrosis is severe, consider removing your infected mushroom coral, as it can be contagious to neighboring corals. 

Do Mushroom Corals Recover From STN/RTN?

Yes, however, it takes time. Recovery from STN/RTN usually takes a few days, but sometimes it can take months or even a year, so sit tight and be patient. 

To speed up the recovery, you can cut off the infected area or dead tissue to prevent it from spreading. 

And now the million-dollar question, how to prevent it from happening…

To prevent it from happening it is pretty simple, remember to frequently test your aquarium water and carry out the pre-treatment advice for new corals (acclimation and quarantine). 


When mushroom corals start turning white, it is either an indication something inside your aquarium is not quite right, such as the lighting or water parameters, or they have experienced a very stressful journey to get to you. 

By maintaining a stable environment and giving them enough time to acclimate to their new home, your mushroom coral will be back to its normal bright colors in no time! 

  • 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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