Black Molly Test not working?

[Connor SKKY02]

Hello,

I have in my QT a blue tang and a black Molly which I turned from FW to Saltwater.
The thing is, every once in a while, I see a very tiny isolated white dot in my blue tang... that disappears in 1 or 2 days... , after 2 or 3 days... another white dot appears in another part of his body again...

Nothing in the molly, no signs of any white dot..... he is perfect....

So now I am in a dilemma.... could it be the Molly is not affected by ich because he is harder than the blue tang? or what I see is something kind of normal skin reaction that usually happen to blue tangs and has nothing to do with any disease, and I shouldn't be worried?

 

[Big G]

Try to get a picture of the next time and post so we can get a look. Lots of possibilities of what the white dot could be: lympho, ich, velvet, brook, flukes. Has the tang been freshwater dipped to check for flukes? It's my usual first step to eliminate or confirm flukes.