I've never found vatf or gatf to be very skittish but im aware of many self injuring armatus. Maybe an individual thing. Regarding temp change, I made a stupid error dropping my tank to the mid 50s and my vatf was unaffected while losing a large black aro and multiple other fish.You may get it backward. It seems that ATF is more skittish than Armatus. From what I learn, Armatus could get stress from tankmate, stop eating and croak, while ATF does not handle temperature fluctuation well.