PLEASE HELP! What is this disease? treatment?

[Lithy]

Four week ago I placed my tangs in a QT to treat ich. There are two fish in this QT which I set up 4 weeks ago for ich with hyposalinity (1.010). The ich spots have been gone for a while and both fish were fine and in the final stage of treatment. Now one of them has developed these blotchy spots on one of his sides (see link) and is lethargic on the bottom of the tank. Breathing is fatigued. Also he has suddenly gotten super skinny...I can see his bones thru the skin. PLEASE HELP!


Please help me identify this disease that appeared overnight on one of my tangs.
http://web.mac.com/robertholloway/iWeb/Site 2/Library.html

Other info.
Like I said they were doing great 2 days ago. 1 is still doing fine maybe just Slightly less active.These are 3 changes I can think of that occurred to the tank in the last few days that may have affected this:
1) I rinsed the PVD and rocks and wiped off the walls to remove some brown algae. I also lightly vacuumed the bare bottom of the tank. bacteria were unaffected and nitrite and ammonia still at zero.
2) I slightly changed their diets from garlic-soaked nori to nori rubbed with some plankton food (the kind for invertebrates, Marine Snow). I fed them this because I read they require plankton for their diet. (back to plain nori now)
3) Due to some crazy whether the temperature of the tank may have had larger than usual fluctuations between 70 and 80F.

 

[Lithy]

Well, I was afraid this would happen and my Tang died overnight. This is my first fish loss and I feel bad....I picked him off the bottom of the tank. He was skin and bones. I do not understand how he could have gone from normal to completely emaciated in 2 days.

Please let me know what I should as precaution for the other one. He is now hiding and I cannot take a good look but I assume he is still healthy.

 

[Lithy]

Asking for HELP AGAIN!!!!!

My other Tang in the same QT set up as described above is showing same symtoms as the one that died. I think he is going to die to. I am reposting hoping that someone with good advice sees this and can post a reply this time.

He was doing very well and I had just started increasing salinity to move him back to the DT...

 

[luke33]

Have you only had your tank for a month and your treating for ick now in a qt? I've had my tank for about a year and a half and i'm still not quite ready for my last fish(powder blue tang). Some fish need a very mature tank before you throw them in, especially a tang like this.

 

[sugartooth]

Not really experienced w/ disease but did you test your water quality?
Again, not 100% sure, but the white patches almost look like burn or something....of course there could be a variety of things that can show up as white blotches/patches.

Ammonia? Low Alk or pH?

Just offering some ideas, not saying that is the reason for the symptoms.....
Good luck!

 

[Lithy]

Clearly the tang died the next day.
Sugartooth, all water quality parameters were fine as I stated before.

This time I took a couple of good pictures of the fish after I pulled him out of the tank. Even though I will be waiting a while before getting tangs again, I would really like to keep them and want to be able to quarantine (and treat if needed) them because they so often have ich. Anybody have input into what this disease might be? Could it be associated with stress from 3 or 4 weeks of hyposalinity? Here are two good pictures of the late Blue Tang, please let me know.

http://picasaweb.google.com/ale.rugge/AlgaeAndTangDisease/photo#5078381666852429922
http://picasaweb.google.com/ale.rugge/AlgaeAndTangDisease/photo#5078381628197724242

Thanks!