Andy Sager
Aquarium Advice Addict
Try to get a head long look at the fish and see if the spots are in the fish or ON the fish. There is a parasite in Saltwater that looks like black ICK so when you look at the fish, the black spots are raised from the skin. Possibly? there is now a freshwater version of this parasite? If you can't really get a good look, net the fish and use a toothpick to see if you can gently rub a spot off. If you can, time to treat. If you can't, and you should be able to tell even before using the toothpick, then it's coloration and nothing to worry about.Ok Bob here are the pics.
Hope this helps