PBT's are known as ick magnets.... Some is urban legend, some is well deserved. They are a PRIME candidate for QT'ing in hypo and/or copper for at least a month after the last visible symptom of ick reared its ugly protozoan head. If it can't make it through QT it wouldn't of made it in the main tank....
I've heard that marinecenter does QT their fish prior to sale so you might have some luck ordering from them. Still, invest in a QT setup....
