Why Is My Leather Coral Shrinking?

Is your leather coral shrinking, and you are beginning to worry if something is wrong? 

Shrinking leather corals is usually normal, however, if this goes on for a long time, and they are not opening up, it may also be the first sign of a problem.

Leather corals are one of the easiest corals to care for, but they can be slightly temperamental at times. For example, if your fish decides to look at them the wrong way, let alone nip them, your leather coral is going to sulk big time!

Why Is My Coral Shrinking?

Sometimes leather corals shrink and half-open or close multiple times when they’re shedding. It may also look like your leather coral is drooping. Shedding is a natural process where they clean themselves by removing the outer mucus layer, similar to how a snake sheds its skin. 

During this time, be patient and ensure your aquarium is well-maintained, particularly the water parameters. Once your leather coral has shed, remove any loose mucus with a turkey baster and run carbon in the filter. The mucus which your leather coral sheds can be harmful to other corals and any fish, so removal is critical! 

As your leather coral continues to shed and produce mucus, your water flow must be moderate and turbulent, otherwise, your leather coral could be fouling in its own waste – another reason it may start shrinking. 

If shedding is not the cause of your leather shrinking, take a look at their neighbors. As previously mentioned, leather corals can be temperamental at times, and if their neighbor is stinging them, they will go floppy and shrink. When this is the case, separate the two corals before chemical warfare happens, or worse, one fights to the death of the other. If you decide to move your leather coral, take extra care, as they are fairly sensitive to being moved around and leather corals release toxins.

Should You Be Worried About Leather Corals Shrinking?

When your leather coral is shrinking, you want to take a close look at its tissues. If your leather’s tissues look healthy and there are no signs of damage or tissue necrosis, then you should have nothing to worry about!

Why Is My Leather Coral Not Opening Up?

Your leather coral may close their polyps for reasons other than they are dying. Stress is the main culprit, which can be caused by a few factors such as pesky tank mates, water conditions, and pests. 


Imagine someone tickling you, all over your skin, you would soon become uncomfortable, right? Well, your leather coral feels the same way! If tank mates start rubbing up against your leather coral’s tissue, or worse, they start nipping at your coral’s polyps, your leather coral will not open. 

To prevent this, always select reef-safe fish. If you are unsure, ask your local fish store (LFS) what they recommend keeping with your type of leather coral. 

Water Conditions

As already mentioned, leather corals have specific water requirements. These include sufficient water flow, lighting, and water parameters. Keeping these stable is key to coral survival. 


To eliminate pests entering your aquarium, you should use a coral dip before acclimating them to their new home. Unfortunately, some critters still find their way into aquariums because they are hitchhiking experts. 

Try taking a turkey baster and blowing around the base of your leather coral to see if anything kicks loose. Any unwanted visitors also pose a threat to other life inside your aquarium, so if you find any, remove them asap. 

Does A Dying Leather Coral Shrink?

If your leather coral is still shrinking after a few weeks, it could be starting to die. 

Your leather corals’ coloration will often tell you if it is dying. Decaying leather corals will start to break down, losing their beautiful colors in the process, appearing dull, black, or white

If your leather coral is dying the algae will start to build up on the decaying flesh. Your leather coral’s flesh may also have multiple holes or chunks missing that start to shrivel around the stalk. If this continues, your leather coral may turn black and detach from its base. 

How Much Light Do Leather Corals Need?

Leather corals thrive in low to moderate lighting (PAR 50-150) for 9-12 hours every day. As your leather coral requires lighting to produce food, without proper aquarium lighting, your coral will shrivel up and die. 

Your leather coral will grow well under T5’s, metal halides, or LED lighting when the proper PAR levels are provided. For the best coloration, a 14-20K color spectrum is recommended, including some blue lighting. Blue and actinic spectrum lighting is the best choice for optimum leather coral color and growth.

When adding your leather coral into your aquarium for the first time, remember your aquarium lighting may be stronger than the one at the store it came from, so if it starts shrinking, it may just be adjusting to its new home. 

If possible, turn down the lighting intensity to prevent moving your leather coral. If that is not possible, move your leather coral to the bottom of your aquascape where the lighting is not so strong, gradually moving it up to its final destination. 


Leather corals are beautiful soft corals that are easy to care for in a well-maintained aquarium. Often these corals like to shrink during the shedding process, which can often look like they are dying, causing concern amongst hobbyists, particularly newbie reefers. 

Keep checking your water parameters and keep an eye on your leather coral, if everything is stable inside your aquarium, it will perk up 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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