OK I have had my 55 running for years now and its very healthy now with no gha or anything. I have 4 chromis, a purple firefish and a lawnmower blenny which are all very healthy. I added 2 healthy percs last night and wake up this morning to see my 2 percs have what looks like ich or maybe something else. All other tank mates show no signs of any problems. i don't know why but everytime i try adding a perc or tang it gets sick and dies. i havent added anything to my tank in quite some time now (months). i see a spec or 2 the size of a salt grain that is clearly ich but i also see raised small lumps on the percs. any ideas?