Why Is My Leather Coral Turning Black?

If you have ever seen photos or videos of coral reefs, or have even been lucky enough to go scuba diving, you have likely seen leather corals. Leather corals come in a variety of colors and types, and the best part, most of them are super easy to care for!

As leather corals are easy to look after, they can also tolerate small parameter swings that many other corals cannot, which is why they are ideal for beginner reef tanks and coral enthusiasts. 

However, leather corals are not bulletproof, and sometimes they get sick, just like us. One of the issues is when leather corals start turning black, leaving hobbyists trying to figure out what went wrong and what to do. If you are in the same boat, do not fear, I am here to shed some light on your problem!

Why Is My Coral Turning Black?

If your coral(s) has turned black very rapidly, it is likely some sort of tissue rot or infection.

There are many discussions if blackened corals are due to a bacterial infection, if it is fungal, or if it is just down to stress. However, it is a common issue among reef hobbyists, so do not worry, you are not the first to experience it, and I can assure you, you won’t be the last!

If your leather coral has turned black, not long after arriving in your aquarium, it may be due to the stress of transportation and acclimation to its new home. It is best to leave it alone for a while and see if it improves. Leather corals really don’t like to be poked and prodded, so if it is turning black from stress, they will recover.

However, if you have been patient, your aquarium is looking nice and stable, and your coral hasn’t recovered, then it is probably an infection like necrosis. Infections like tissue necrosis must not be left alone, they require some TLC.

What Is Coral Tissue Necrosis?

There are two kinds of tissue necrosis depending on the speed of the infection: slow tissue necrosis (STN) and rapid tissue necrosis (RTN). 

Necrosis happens when your leather coral loses its skin/flesh, which starts melting the coral or exposes the skeleton in stony corals (LPS and SPS corals) that have a calcium carbonate skeleton. 

What To Do If Your Leather Coral Turns Black 

If your leather coral is turning black from an infection, you want to act fairly fast before it turns into a poof of ash, or worse, infects your whole reef tank. 

First, grab a pipette or turkey baster, and see what blows off of it, removing any debris. If nothing happens, remove your leather coral from the water and give it a quick coral dip and light scrub with a very soft bristle toothbrush – toothbrushes for toddlers work wonders!

If your leather still shows no sign of improvement, it is time for some minor surgery from the reef doctor – you! Many hobbyists find that cutting black parts off of leather corals provides them with a full recovery in a well-maintained environment.

Carefully cut into the healthy flesh of the coral above or below the infected black areas of tissue with a scalpel or knife, and discard the infected tissue. Do a quick coral dip and siphon aquarium water around the cut area to check you haven’t missed anything. Place it back into the aquarium and monitor it, if it keeps turning black, consider discarding it. Which, trust me, I know is a hard decision to make!

How Do You Know If Your Leather Coral Is Dying?

The color of your leather coral will give you a good indication if it is dying. Corals that are dying will start breaking down, and they will exhibit a lack of healthy color. 

Common Signs & Symptoms Of Dying Leather Corals:

  • Sometimes algae will build-up, on top of the coral’s polyps. 
  • Decaying/rotting flesh that is softened, crumbling, or flaking.
  • Significant discolorations of the flesh. 
  • Holes or missing chunks in the flesh.
  • A shriveled stalk that starts caving in.
  • Coral detachment from the base.

If you are worried about your leather coral dying, you can also take a good look at your leather’s polyps. If your leather coral has a normal deflation, it will return to its normal shape and size relatively quickly, but if an abnormal deflation occurs, your leather coral may result in a body-shape deformation or death. 

How To Prevent Leather Corals Turning Black?

Aquarium stability is key, and usually the answer to many problems. Take a look at your water parameters, are they in the following ranges? If not, perform a water change and dose your aquarium where needed. 

Leather coral water parameters:

  • Temperature: 76-82℉
  • pH: 8.0-8.4
  • Salinity: 1.025
  • Calcium: 350-450 PPM
  • Magnesium: 1250-1350 PPM
  • Nitrates: <10 PPM
  • Phosphates: <0.10 PPM

Next, check the water flow and lighting. Leather corals thrive in low to moderate lighting (PAR 50-150) and moderate to high flow.

Your aquarium lighting may be stronger than the one at the store it came from, so your leather coral will need time to adjust. Try turning down the lighting intensity as leather corals do not like to be moved around, if not, move it (very carefully) down the bottom of your aquascape where the lighting is not so strong. 

Sufficient water flow also keeps your leather coral healthy. You want to ensure it is strong enough to keep detritus off your coral’s tissues, but not too strong that your leather is being blasted, as this can tear your coral’s tissues, exposing it to bacterial infection, and in severe cases, death. 


If your leather coral is already established and has started turning black, it is most likely an infection or tissue rot and should be removed, followed by gently blowing the area with a turkey baster or physically removing the black area(s) to prevent the infection or rot from spreading. 

Remember that stability is key in aquariums, especially with leather corals that do not cope well with drastic changes in lighting, flow, and water chemistry. By following the above guidelines, your leather coral should bounce back to its normal, happy, and healthy self!

  • 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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