Corals that exhibit receeding tissue should always be a sign of concern, but with the proper husbandy and appropriate actions, they don’t necessarily have to be a sign of doom. A dying coral can be brought back from what would appear to be be a sure death, but we need to figure out what’s going on around it so that the right actions can be taken. Is the coral being stung by a nearby coral? Is it responding to some change in the environment, such as new light bulbs? Is the coral getting enough nutrients or is the aquarium full of the wrong kind of nutrients? There are a million different reasons why a coral may take a downturn, and regardless of the reasons the coral should never be seen as a lost cause. Troubleshoot water parameters, undo any new changes that can be undone, and try to get the aquarium back to how it was prior to the coral’s decline. Typically, the coral will respond within a couple of days. Just make sure you don’t try to change too many things at once, otherwise you won’t know what fixed the issue.