Anglers can be difficult sometimes, as many are lost due to a little-understood "disease" known as SAD (Sudden Angler Death), where a seemingly fine fish begins darting around the tank, bloats, floats, and dies within short order. Sometimes for whatever reason, fish from the same supplier all have issues, sometimes not.
Did all of your fish come from the same place?
How long did you have them before they presented?
I've never known anglers to be prone to ****** personally, are you sure it was ******?