appear to be under and not on top of the skin? I would advise you to still perform hypo salinity in a QT tank. Do a search on this and how to perform, you could do that or treat with copper depending on what the outbreak is, but DEFINATELY do not, i repeat, do not treat your main display tank! When you say your levels are GOOD with the exeption of trates.... do you mean like.... ph-8.2, ammonia-0, nitrite-0 and nitrates-20... or something worse? Also you never gave your tank size, which could play a big role in the outbreak among other things