Powder Brown Tang in QT (Ich + Black Ich)?

[AJtheReefer]

I need some help. . . .I introduced a Powder Brown Tang into my QT tank 3 days ago. He is currently in SG 1.009 on Hypo treatment. . .

The tang was very healthy (plump and round) at the store and started eating right after acclimation. I drip acclimated very slowly for 3+ hours.

Some information about the situation:
- The QT is a 20 gallon (with a power head, power filter, and HOB reactor running some sponge and carbon for additional bio filtration)
- The Powder Brown is around 3"
- There is a small 1" or so Orchid Dottyback in there as well.
- The QT is bare bottom with various pieces of PVC
- SG was lowered from 1.020 to 1.009 (or 12ppt) in a period of over 2.5 days

Now the symptoms:
I saw around 10 or so white spots on the tang's body and a couple more on one of his side fins (this happen on the following day after introduction). What is strange is that the white spots went away in a matter of hours? I thought ich would stay for a day or so, at least. I was lowering salinity for the hypo treatment when the fish showed the white spots.

Now I see some very tiny small black specs on his body. I don't see those specs moving and I don't think the specs have increased. You can only see these specs when the tang is pale and not in full coloration. (The tang changes color throughout the day).
Could this be normal pigmentation, Black spot disease, or some marks from the white ich? Can the fish have both diseases?

I rather not stressed out the fish by doing Formalin and/or FW dips to treat black ich, if it is not absolutely necessary.

The fish seems to be swimming normally and is eating well. Some times I see the tang scratching, but it is not doing it constantly. The Orchid isn't showing any signs of any disease.

What would be your recommendations?

Thanks you for helping. . .

[kevin2000]

My 02

I think you have the situation well in hand and would sit back and simply observe. If you have black ich its pretty easy to treat and does not have the same nasty reputation as normal marine ich.

In the even you have black ich you can simply give the fish a series of formalin or FW dips later in the QT process.

[AJtheReefer]

Kevin,
Thanks for your response.

I was leaning towards observation. But the scratching is increasing, so after doing some research on Black ich and a recommendation from a local fellow reefer I will be trying a FW dip with methylene blue on it.

Will report progress later on.

[AJtheReefer]

I did a 10 minutes FW Dip and the small specs are still there.

For now I will assume that the specs are natural pigmentation and I'm not dealing with Black ick.

The Fish seems to be fine, after the dip the fish was in a corner acting stressed. After 3-5 minutes, he started swimming normally.

I think the scratching is due to the white ich. Hopefully he gets better after a day or so due to the hypo. salinity