It could be a few different issues. For example, it could be Ichthyosporidium, a fungus, or flukes. Each need a different treatment, so it is important to properly diagnose it. I have a link below for you to look at.
At the top of the page on the link below, you can click on the various diseases and it will tell you a little about each of them. If you need any help with figuring out which your fish has, I'd be glad to help you, but I would need to know the symptoms of your fish besides just black spots.
Also, most fish diseases are caused by water quality issues. What are your water parameters? Mostly I need to know ammonia, nitrates, and nitrites.
You will need to set up a hospital tank if the sick fish isn't the only fish in the tank. If you don't have one set up already, you should use 1/3-1/2 of your one tank's water and fill the rest of the hospital tank with spring water. Don't add any decor to your hospital tank. Transport your cichlid with water in a bowl or something, so as not to stress it out anymore.

Please let me know if there's anything else I can help with.
Freshwater fish diseases

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Phishie

"An ounce of prevention is worth a pound of cure."