Hey saltwater aquarium fans,
Compared to saltwater aquarium fishes coral problems can be much more difficult to identify and diagnose. Even in the wild not much is known about coral diseases, what causes them and how to cure them.
As luck would have it (or not) most coral problems are caused by poor water quality that will most likely go away by themselves when conditions are made more favourable.
The most common issue is excess nitrates and/or phosphates (and more rarely ammonia or nitrites; although these should not be present in an established aquarium with a decent biological filter set-up) fluctuating parameters also cause corals distress. Other parameters to check immediately are temperature and pH.
Poor water quality will cause stress, which can be a causative agent of disease too. This is another reason a detailed water quality analysis should be carried out as soon as you witness any coral problems.
The other main factor that causes coral problems is inappropriate lighting. This will be from either aging bulbs putting out the wrong spectrum of light (the spectrum slowly changes as they age) or a new coral placed in an area where they get not enough or too much light.
A new coral can be positioned toward the bottom of its light “range” and be gradually moved up, staying in each position for several days to a week. Take a photo at each position, at the end the photo will tell you which position the coral is most expanded in; this will be your perfect placement!
Poor and/or fluctuating water quality and wrong lighting are the most common causes of stress; other common coral stressors are incompatible tank mates, starvation, physical damage and poor water flow.
So remember if you have a diseased coral in your marine aquarium the first thing you should do is check and remedy your water parameters before treating the symptoms!