Severe ich in just a few hours??

[GregJames]

What could cause a perfectly healthy yellow tang to go from playful and hungry, to covered in ich and almost white in just 12hrs??

The only change to the tank was upping the calcium by quite a bit, but I didn't think that would affect the fish..

 

[gone fishin]

Is this the only fish in the tank and how long have you had it? Any other symptoms.

Since you increased calcium quite a bit is it possible the fish is covered in calcium precipitate?

Otherwise the ich has been in the tank and has now made itself known. A picture would probably help.

 

[billdogg]

^^^What he said^^^

How much is "quite a bit"? Although I wouldn't expect it to stress a fish to that point (unless in was a huge increase), Tangs get the moniker "Ich Magnet" for a reason.

If it is, indeed, Ich, the only recourse will be to remove all fish for treatment to a Hospital Tank and leave the DT fallow for a minimum of 72 days. I prefer the Tank Transfer Method (TTM)

 

[GregJames]

Strange... I just woke up (I work nights), and he is completely clear of spots, color has returned, and he's swimming around like crazy.

Last night he was COVERED in tiny white specs and he was just a very light shade of yellow.

 

[jrr98002]

Although I've never seen this happen personally, by upping your calcium by 'quite a bit' it sounds like he may have been covered in calcium carbonate. Hope the spots don't return.

 

[GregJames]

Well... By quite a bit, I may have gone from undetectable to 450ppm in about an hour... :-/