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Why Your Leather Coral Is Not Opening!

After publishing our article going over why your coral is not opening up, we have noticed a large number of people specifically asking why their leather corals are not opening up so we wanted to publish a dedicated article on leather corals.

This is due to leather corals being such a common option for people new to keeping coral due to their hardy nature and many people new to corals failing to realize just how sensitive a “beginner friendly” coral can actually be!

The most common problems that can prevent your leather corals from opening are poor water parameters, unsuitable water flow, unsuitable light intensity, and tank mates nipping or eating the coral.

In some situations, problems with nutrition levels and water temperature can also come into play. In some situations though, some leather corals will just take longer to open up than others and in rare cases, this can be months longer than other leather corals.

If your leather coral has been having problems causing it not to open then your leather coral may be dying and our article on how to stop your leather coral from dying may be worth reading if you feel that this may be the case.

Although it is not the most accurate method to gauge a coral’s health, some people do use the “sniff test” for their corals and if your leather coral has a sour smell to it then it could be an indication of a problem.

One thing to note is that there are other reasons that your coral may have a sour smell that are related to poor water parameters in the tank rather than issues with the coral itself.

Is It Normal For A Leather Coral Not To Open Up?

In rare situations, it can be totally normal for a leather coral not to open up even if all conditions within its tank are perfect for it.

Leather corals are usually considered to be one of the more beginner friendly corals due to their hardy nature making them easier to care for but every now and then, a leather coral just refuses to open up no matter what you try.

As we covered in our article on zoanthids not opening, it is totally normal and natural for a coral to close up if its water parameters or light intensity is not optimal for its needs.

This is a natural defense system for the coral to try and protect itself and is an obvious indication of a problem within the aquarium that needs to be corrected as soon as possible.

If the fish, shrimp, snails or other creatures in your tank are constantly harassing your leather coral then it is also considered normal for the coral to close up and refuse to open until it feels safe.

Problems with water parameters can be more tricky as there are multiple water parameters at play that can affect leather corals in different ways causing them to do different things and depending on the levels of certain parameters, the coral can be open or closed but still have problems.

How Long Does It Take Leather Coral To Open?

Most leather corals in a new tank should start to open up within a week of being in their new home with some taking as long as a month without this being considered a problem.

If your leather coral has been in its tank for a couple of months and has suddenly closed up for more than two days then this is a sign of a problem either in the tank or with the coral that requires attention.

Some leather corals will take to a new tank much quicker than others and unfortunately, this is just one of those things and there is usually nothing you are able to do about it.

It can be common for reef tank keepers to get multiple leather corals on the same day, place them in the same tank with one to open within a day or two, one to open within a week, and one to take much longer.

It’s just the way that corals are and even though leather corals are more hardy than other corals, they can still be temperamental and act erratically even if you think that all conditions in the tank are optimal.

A common mistake that some people new to keeping corals can make is to use a cheap water test sticks rather than an actual reef water test kit giving them the impression their water parameters are fine but those cheap stick kits can be highly inaccurate and don’t test all water requirements.

Why Won’t My Leather Coral Open?

If you are having problems getting your leather coral to open up then you should check that your coral is in an area of your tank with moderate to low water flow.

Although leather coral can tolerate most lighting conditions in an aquarium, they definitely tend to do better with a moderate light intensity do avoiding a high or low light intensity may be a good idea until the coral has initially opened up.

As we covered in our article on flower pot coral not opening up, you may find that you have accidentally added a non-reef safe tank mate to your aquarium that is eating or nipping your leather coral.

This is more common that many people who are new to keeping corals initially realize and it can end up being a problem as you may be stuck with a coral eating tank mate that you have no where else to home in a tank full of corals.

Balancing the water parameter requirements for corals can take a little getting used to if the majority of your aquarium keeping experience is based around fish only tanks without any plants in them as corals tend to prefer “dirty” water.

In this instance, the term dirty does not actually mean dirty in the traditional sense but not what most people will consider optimal for a tank with just fish when it comes to their nitrate levels.

It can take a little playing around to get the ideal water parameters to get a problematic leather coral to open though but it can definitely be worth it in the long run.

How Much Light Do Leather Corals Need To Open?

It is a common misconception that leather corals will open in any light and although this can be correct for some leather corals, it is not always the case.

Most people will find that they will usually have a better chance of getting their leather coral to open under a moderate intensity light before changing their lighting intensity to low or high intensity.

People commonly use the fact that most types of leather coral can tolerate and live under a wide range of lighting intensity to back up their theory that leather coral will open up under any light intensity but this is simply not correct.

If you have a leather coral that is not opening up then a high light intensity is unlikely to help the situation and in our opinion, should be avoided until your coral has opened.

You can still get a leather coral to open under a low intensity light but you will probably have a better success rate by going with a moderate light intensity and just leaving your lighting until the coral opens.

We know that this is not possible in all tank setups though due to the lighting requirements of other corals, anemones or fish in the tank so you will sometimes just have to work with what you have and do your best when it comes to lighting.

Will A Leather Coral Open Up In A Low Nutrient Tank?

An old trick to get a leather coral to open up is to actually reduce the nutrient levels in its tank to get the coral to open up to try and absorb more nutrients from the water.

This trick can work but it is not as reliable as some people claim and you have to factor in the nutritional requirements of the other corals and fish in your tank if you do try this strategy.

We usually don’t recommend that you try this even though it is commonly recommended on social media to people having problems with their leather coral. This is due to most people who have problems with getting their leather coral to open being new to coral keeping.

They may not have the experience required to balance nutrient levels accurately making this more of a gamble with a low pay off potential and potentially high risk depending on what else is in the tank.

You also have to make sure that you have tried absolutely everything else as reducing the nutrient level in your tank in an attempt to get your leather coral to open up is unlikely to do anything if the coral is not opening due to water flow, lighting issues, or a tank mate eating it.


That brings our article going over why your leather coral is not opening to an end. We hope that we have been able to help you better understand the more common reasons that your leather coral will stay closed as well as the various things that you are able to try to get your coral to open up again. Unfortunately though, as we touched on earlier in the article, some leather corals can just be really picky and stay closed even if everything else in their tank is perfect and you just have to deal with it sometimes.