Rescuing Dying Corals: How to Guide

So you found a rescue coral – now what?  The majority of rescuing a dying coral is similar to just caring for a healthy one with good water parameters.

Preparing the Coral

When the coral arrives home, you’ll want to acclimate it first. I find that with rescue corals, a 15 minute temperature acclimation is ideal (no more, no less). These corals are often damaged from poor water conditions at the store, so it is best to remove them from the cause as quickly as possible.  If they were damaged from other conditions (high light, stinging, etc.) then this short acclimation is not as important.  After acclimation I dip the coral in CoralRx (or some other coral dip). 

After the dip I remove almost all dead skeleton and base rock.  I find this especially critical with rescue corals.  In my experience, corals have an easier time growing new skeleton than growing over old skeleton, especially if the old skeleton has sharp edges.  If the coral is in strong flow, the coral’s tissue could catch on a sharp edge of its old skeleton and rip.  For example, removing the dead skeleton of the scolymia below could severely damage the coral, so I trimmed down the sharp points and left it alone.

Place a small amount of superglue over any tissue that has ripped.  This will help prevent water flow from literally ripping the tissue off the coral.  Superglue reacts with water and forms a type of plastic mesh.  However, this reaction is exothermic, which means it releases heat.  This heat can cause cell death, so extreme care should be used around rescue corals.

In-Tank Care

When you first place the coral in the aquarium, you’ll need to keep hermit crabs, cleaner shrimp, and the like away from the coral.  These critters go after the dying tissue and often take away healthy tissue in the process which can quickly lead to the coral’s demise.  You’ll also need to keep them away during feeding – a shrimp stealing food from a coral’s mouth can be very damaging.

Lighting and flow should be low to allow the coral to acclimate.  You’ll need enough flow to keep the coral mucus from building up on the coral though.

Stung Coral Care

Corals stung by another coral are probably the most easy to save.  These corals are healthy overall, but a portion of them is damaged.  As long as infection is avoided and no further damage occurs, then healing is rather quick.  When corals are “stung” by another coral, they are usually actually “digested”.  When corals have to compete for territory, they expel their external digestive organs, mesenterial filaments, and use them to digest a nearby coral.  This typically results in one area of severe damage and no damage elsewhere.

This orange Fungia was likely stung by another coral.  The remaining tissue is very healthy.  I used superglue to secure the edges of loose tissue.
Water-Deteriorated Coral Care

Through the stress of shipping and poor water conditions many corals start to deteriorate.  This is typically a slow process that results in the tissue between polyps receding first followed by the outside polyp ring (see below – the purple ring is dead skeleton).

With these rescue corals, good water parameters are essential.  These corals typically do not need much additional care.  Just keep nuisance algae off the dead skeleton.

Bad Fragging Coral Care

When a coral is improperly fragmented, various outcomes results depending on damage.  Sometimes the tissue rips apart where it shouldn’t, or the skeleton is broken underneath intact tissue.  As long as there is about half the polyp left, the coral typically survives with the natural healing process.  Use superglue (with the cautions mentioned above) to seal fly-away tissue to the skeleton.

Pest-damaged Coral Care

Pest-damaged coral rescues are risky in that the pests may infect your other corals.  Please do not attempt this type of rescue without a proper quarantine tank and medications on hand.  Typically, once the pest (and eggs) is removed the coral will heal quickly on its own.

Infected Coral Care

I highly advise against purchasing an obviously infected coral unless you have a dedicated hospital tank, have lots of experience in rescuing corals, and don’t expect too much.  Infections vary by cause (bacterial, viral, fungal, ciliate, etc.)  Some examples of disease are black band, yellow band, white band, Vibrio, zoa-pox, etc.  Be cautious as some are even transferable to humans.  The only infection I would knowingly attempt to abate is zoa-pox as it has a well-proven treatment of Furan-2.

Bleached Coral Care

Coral bleaching has a variety of causes, and knowing the cause helps determine the solution.  High light, severe low light, high temperature, low temperature (rare cases), lack of oxygenation, and even a Vibrio infection can cause bleaching.  If you do not know the cause for the bleaching, treat the coral as if it was bleached by high light.  Place the coral in a low light area but with sufficient light for photosynthesis.
Since a bleached coral is lacking its typical zooxanthallae population (the symbiotic algae that lives inside the corals tissues and produces food for the coral by photosynthesis), it will need regular feedings like a non-photosynthetic coral would.
When I am first dealing with a bleached rescue coral, I dose the recommended amount of amino acids to the tank.  This elicits a feeding response from most corals.  One hour after dosing I turn off all flow in the tank.  I drop a couple of fish food pellets onto the mouth of the coral (feed all mouths if the coral has multiple.)  Bleached corals have nearly zero energy since they are starving.  Placing food directly on their mouths limits the amount of energy they have to expend trying to catch food.

The coral should accept the pellet, but often it will not initially.  If the coral does not accept the pellet, remove it after approximately 30 minutes so it does not rot.  Try this again an hour or two after the lights have gone off on the aquarium.  Most corals feed at night, so this may help.  If the coral does not respond to food within a couple days, place the coral in a small container filled with tank water and place the best thawed frozen food you can find in the container.  The water should be a bit cloudy with all the food.  After a few minutes, place a bit of the same food on the mouth of the coral.  If this still does not work, the coral is not likely to survive.

If the coral readily accepts pellet food, move on to a blended frozen food thawed and mixed with saltwater.  This is more like what a coral catches on its own in the wild, and I’ve found the corals digest this better than pellet food.

Ethical Dilemma

In 2011 a controversy erupted on a reefkeeping forum as to whether rescue corals should be bought.  The belief is that buying rescue corals from local fish stores encourages the stores to sell inferior products.  I highly disagree with this, but I encourage everyone to develop their own view.  Most fish stores sell damaged corals at a drastic price reduction, and I see no problem with buying their corals.  The stores can’t easily give away dying corals since they cannot claim a loss.  I do have a problem with the stores that sell bleached corals as “rare white corals” for full price.  Obviously that is an issue, but those cases are few and far between.

Do whatever you believe is the right thing, and pay only what you feel comfortable losing for a rescue coral.

This blog was based on my thread, Rescue Corals, ReefCentral.com’s February 2011 Thread of the Month.


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  1. Anonymous

    How do you save a meat/doughnut coral if it is missing a mouth? Originally it was held in a tank with a filefish and the fish kept picking on the mouth of the coral. The skeleton where the mouth use to be is exposed and you can see a bit of algae on it. Also the edges of the coral is starting to lose its flesh. I currently have it isolated from all critters in low flow and light(shaded). What are the chances it will recover without a mouth?

  2. Reef'd Up

    I'm so sorry to hear you're having difficulty with your meat coral (I assume scolymia/acanthophyllia?) Unfortunately, I have not yet found a way to save corals missing their entire mouths/digestive system. The good news is that it's in your aquarium already, where it will have the greatest chance of survival (no acclimation stress). If there is still some mouth tissue/digestive system left, it may be able to regenerate itself. I would try giving it some food to see if it has a feeding response. If it does, it may have a chance. If it does not respond, then it may be too far gone (don't force food into its mouth as it will rot and kill the coral faster.) Feel free to send any photos to me at ReefdUp@gmail.com or post on the thread on RC (link above.) Best of luck to you!

  3. Anonymous

    Thank you for the quick reply and suggestions. I've tried squirting rotifers when the lights are off and not sure if it is accepting it. I notice that there isn't much extension because I can still see the the flesh flapped over it's skeleton and not inflated like a healthy coral would. I took you advice and apply Krazy glue over the dead skeleton and receding flesh hoping to stop the withering of flesh. It's currently being isolated in a quarantine container with vents for water flow to seep through but so far not much improvement that I've notice. I will try and e-mail you a pic next.

  4. Reef'd Up

    Please email me or send me a link to the photo – it's much easier to see exactly what's going on that way. If you have any amino acids (I use Zeovit's product), I'd dose them about an hour prior to lights turning off. It'll help signal to the corals (along with the darkness) that it's time to eat. About an hour after the lights go off, turn off all flow, and drop a couple fish food pellets onto the coral's mouth. Leave them for about 30 minutes. If the coral does not eat them, then blow them off gently with a turkey baster. If it does accept them, keep feeding until the water has been off for 30 minutes. If the coral still won't eat, try placing the coral in a small container of tank water and tons of various foods. People do that frequently for non-photosynthetic corals that refuse to eat with great success. I'd only leave the coral in that container for about 15-20 minutes. If it still doesn't eat, repeat that every day. But, send a photo, and hopefully we'll figure something else out just in case it still won't eat.

  5. Anonymous

    Sorry for the late reply back but could you post your email address? I could not find it on this blog site.

  6. Reef'd Up

    Sorry…I can't find a link to my email on here either! There used to be one. Anyway, it's reefdup@gmail.com. Hope it's not too late. :-/

  7. paul

    my Duncan coral has a small srape/tear on its side. I gave it a quick rx dip. now a stringy substance is present from wound, any suggestions would be greatly appreciated, great article by the way.

    1. admin

      Hi Paul! Thanks for reading, and sorry for the delay in response! How is it looking now? Is it a white stringy substance? If so, it’s probably the coral’s mesenterial filaments, which are basically part of the coral’s digestive system. No worries though – it’s not like if our intestines were hanging out! Corals extend these filaments when stressed or even when fighting. If you have further questions (or want to send a photo), my email is reefdup@gmail.com. Good luck!

  8. paul

    thanx for the knowledge, right now its mostly closed but has opened up a little from time to time. it does have tiny duncans on its side that are mostly open. maybe if the skunk shrimp would stop grazing it. ive read they can stay closed for periods of time, not sure, only three months in to hobby. thanx again for your time and knowledge

    1. admin

      No problem! Welcome to the hobby! I’ve heard that about Duncans, but I’ve had my colony for 7 years, and I’ve never had them stay closed for more than a day. Again, feel free to email me if you’d like to have me double check anything. :) Good luck!!

  9. forever_jade25@yahoo.com

    How do you go about cutting off the exposed skeleton of a coral saved from a pet store? I just recently bought a meat coral with exposed skeleton, he is doing very well in my tank but wasn’t sure if I should let the flesh regrow over the skeleton or cut it off.

    1. admin

      Hi! Honestly, I would just allow the coral to regrow over the skeleton if it’s a meat coral (assuming it’s probably a Scolymia, Acanthophyllia, Cynarina, or maybe a Trachyphyllia (previously named Wellsophyllia)). These corals do not take well to additional stress, especially if you are not extremely experienced with the proper tools. I do not recommend bone cutters for this as meat coral skeletons are usually very thick (which means you could accidentally crack the skeleton under the coral tissue with the bone cutters.) I use a diamond-blade band saw made for lapidary work (the Gryphon C-40). Even with this band saw, I do not remove the skeleton from Acanthophyllia – it is too high of a risk. Hope that helps!

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