Lost a fish in QT
 

Lost a 1.5" Potters after 18 days in what I thought was going to be a foolproof QT (converted 20G refugium, ~10lb LR with CSS65 skimmer). Found this morning when getting ready to do what would have been my 4th 5g change.

Was eating, looked good, active maybe a little faded in colour from when I got it. Only thing was last couple of days seems to be hiding a bit more when I was in the room. SG and temp good, NO3=0.0, all I had for NH3 test was an expired Hagen so wouldn't bet a 100% but measured zero.

Ideas?

Sorry to hear about your loss.. Could have just been stress... faded color.. hiding... smaller tank then it been used to.... change in water chemistry ... cyanide caught???

These are tough fish to keep and I have shared the same experience.
Here is a recent article (Part 1) on Marine Angels.

http://www.advancedaquarist.com/2008/1/fish

Did you know that the Passer grows to 18 inches?