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.
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.
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.