I know this is a bit of an older thread, but I'm going to re-open it because I've been pondering this species.
@Beastije , how are things doing?
@Byron , Do you have a source for the Compatibility/Temperament info you provided here? Just curious, as I too have found conflicting info about this species, even among reputable sites. I suspect it has a lot to do with how they are kept and how much room they are given, as you mentioned.
You make a good point about expecting fish to act normal. However, I believe that the OP was trying to determine what "normal" is for this species, as their normal behavior seems to vary widely depending on whom you ask. Seriouslyfish says that while similarly shaped fish should be avoided, it "can be maintained alongside peaceful, schooling species with comparable environmental requirements."
Domestication and other selective breeding can indeed alter the genetic makeup of a species, and thus its behavior. But whether this is the case with paradise fish, I don't know.