Terry,
Thanks for the input. I was under the impression that it may be due to the netting of the fish. I took it home the day after it was put in the LFS tank, but it already had those marks. Obviously it was netted by them when they took it out of the tank; I didn't net it as it went straight into QT. I wasn't too concerned with the markings as I am aware that tangs under stress are also prone to ich. I am not using vitamins or selcon at the moment, but I will do some research today and follow up.
I feed the fish mysis shrimp, emerald entree, brine shrimp, cyclopeeze, bloodworms, nori, and veggie flakes. There are several pieces of PVC in the tank (the pics are only showing one side of the QT.) I have a standard 17 watt light over the tank; nothing fancy. It stays on 10 hours a day. The tank is in a located behind my bar, so there are no external stresses other than me approaching the tank (usually it gets fed, so it sort of looks forward to my presence.)
I am measuring the salinity with a refractometer. I checked the calibration yesterday with distilled water; it checked OK. I am going to follow Dr. Farley's recipe for making a calibration standard close to NSW today.
Again, thanks for your input. Let me get going and check up on some vitamins and selcon.
Brian