It's been less than 24 hours...so not exactly a scientific conclusion... But the 2 groups with odd numbers are more peaceful so far, there might be something to this. The neons and red eyes are keeping tightly together while the Glo fish / danio group of 8 are definitely chasing each other around a bit. I know they're much more active fish which probably has something to do with it, but there might be some truth in all of this. If they still chase each other in a week, I'm gonna go get another danio and see if they calm down in a group of 9.