Global warming and environmental pollution has not left the coral reefs unharmed. Those who say that aquaculture is the biggest threat to extinction of some coral species need think again. Most part of the coral reefs in natural water bodies are being harmed at an alarming rate and no serious measure have been taken yet. When identified to have caught a disease, all aquarists take proper measures to cure and make the coral recover soon. Call it the dread of loosing bucks spent over it or the efforts put in setting them up, they are safer in reef tanks than in natural habitats. I am not saying that they don’t die in artificial set ups but the chances for survival and recovery is more than seas and oceans. To get a coral treated properly when it has caught a disease, one must know the symptoms to determine which the bug causing element is. Here we shall be discussing the most found coral diseases.

Black Band Disease

The widely known cause of this disease is cyanobacteria combining with another bacterium called Phormidium corallyticum. A black band or line 5-40mm wide appears on the coral. The coral in front of the moving ahead band is healthy looking, while behind it the coral is dead and looks white. The band can move across the coral colony at a rate of 4mm a day. The band actually consumes the tissues as it moves along the surfaces. Soon after you will begin to see the skeleton of the coral exposed. Though this is a SPS disease it can affect many different species of some LPS corals too. Coral families that are most affected by this disease are Pocilloporidae, Acroporidae, Faviidae, Poritidae, Pectiniidae, Mussidae, Dendrophylliidae, Siderastreidae and of the orders Alcyonacea and Hydrocorallina.

White-Band Disease

This disease is identified by white bands or patches and spots of white that usually start at the base of the corals. As the disease severs it progresses upward till the tip and consumes the tissues as it goes living behind the skeletons. This too is found mostly in SPS. This is a very threatening disease in Great Barrier Reef. A similar disease called white plague has had a major impact on Caribbean reefs and is said to be the potential threat of the region. It worsens at a rate of 1/10th inch or more per day. Major victims of this disease include Pocilloporidae, Acroporidae, Faviidae and Poritidae.

Yellow Blotch Disease

In this disease yellow circular spots start appearing on the base of the coral and gradually start turning the coral into pale yellow translucent color. The spot begins to grow wider with the worsening of disease and the skeleton becomes exposed. The bacterium that is associated with yellows blotch disease is said produce pale yellow lesions and in due course kills the zooxanthellae algae inside the coral. This deprives the coral of its ability to produce food by photosynthesis process. This weakens the coral which may die if left untreated. This disease mostly distresses some of the star corals and brain corals but can be found on other types of LPS and SPS.

Brown Band Disease

In this disease the corals are divided from between by a brown band that creates a gap from where it starts consuming the corals. The band grows as it consumes the tissues and exposes the skeleton. The brown band is caused by thick populations of single-celled organisms called ciliates that are enclosed with cilia. The ciliates eat the symbiotic algae within coral polyps. The ciliate Helicostoma nonatum may cause the disease which appears as a brown jelly-like condition on aquarium corals. At least 18 species of Acroporidae, and a few species of Pocilloporidae and Favidae are endangered by this disease.

Coral Bleaching

In this disease the color of the coral becomes translucent allowing the skeleton to be visible. It occurs when zooxanthellae are lost from corals and the major reasons could be increases in lighting, ultraviolet radiation, excessive temperatures, extreme temperature alteration, tremendous salinities, severe changes to the salinity, too high levels of water flow and bacterial infections. If left untreated they are extremely fatal to corals. Bleaching occurs more in natural habitats than in aquariums.

While these are the mostly seen diseases in corals there are more like Skeletal Eroding Band, Aspergillosis, Dark Spot / Black Spot Disease, Black Necrosing Syndrome, Pink Spots, White Pox and Coral Tumors. If treated properly in the initial stage, the corals are seen to recover.