Help with my new Naso Tang

[boostedirl]

I purchased a Naso Tang and Fox Face on Saturday. I brought them home, setup a quarantine tank with a sponge filter that's been in my established reef tank's sump for about a year now, a maxijet 1200, and a heater. Up until today both fish have looked healthy, eat like crazy, and seemed normal. Tonight before going to bed I noticed the Naso can't maintain buoyancy at all. It's swiming around barrel rolling and looks to be breathing very heavy. I test parameters and they are: Temp 80, SG 1.025, Nitrate 0.02mg/l(ppm), Nitrite 0mg/L, pH 8.2, and Ammonia less than 0.25mg/L. Below is a video of what the Naso was doing. From Saturday until earlier today it appeared fine and would eat just fine, then tonight all of the sudden this happened. Any ideas?

Click on the picture and it'll take you to the video. I couldn't get the embed feature to work

 

[boostedirl]

After monitoring the fish some more I just lost the Naso Tang. I attached a pic to see if that helps anyone determine a cause as to what happened. So far the Fox Face still seems fine. I did a water change as soon as I pulled the Naso out. I'm so bummed right now. These are two of my favorite fish. Hopefully the Fox Face continues to be ok. I'm hoping I can get a hold of the store tomorrow and they'll work with me on this. Any help as to what might have happened is appreciated. This is the first time I've lost a fish like this. I've been in the hobby for three years and this is the first loss I've went through like this so I want to see if there is any way to avoid it happening again in the future. Thanks for any help you can offer.

Here is the unfortunate final end to the Naso:

 

[Deinonych]

Sorry for your loss.

How did you acclimate the fish?

 

[enjetek]

acclimation might be an issue or how it was collected - you might never find out sadly. barrel rolls are usually bad though. maybe he got stung but i doubt it could be that.

 

[angelfish7]

that fish looked like it was poisoned either when it was captured or stun by the foxface.!

 

[boostedirl]

I drip acclimated like I have before. I setup a container next to the tank and drip with an airline tube about 3-4 drips/second double the bag water, emptying half after that, then doubling the bag water again until the salinity matches. Overall, the process takes no more than hour. I've acclimated all my fish this way and never had an issue. This is the first time this has happened.

 

[MrTuskfish]

Nasos are one of the few tangs I've never kept; but Nasos croaking during acclimation seems quite common on our forum. He also looks very thin to me; but I'm not that familiar with the fish. It could be collection, cyanide is still used some places; as suggested by angelfish7 above. I always want to know the origin of fish and avoid some places. Indonesia (Bali) , The Philippines, and "Indo-Pacific" top that list. I really doubt you'll ever know for sure what happened.

Just to save you a few cents an some time: there is no reason to test nitrate in a QT. Nitrate isn't harmful to fish at any level you'll ever see in a QT.