Exactly why I'm wary adding more to my cherries.I had "killer cherries" once too, I was shocked! I'd kept them before, little peaceful fish. My "evil" males were super red all the time, I wondered if they'd been hormoned or something after the dominant male killed the others, M & eventually F. Of course, I think they were among the largest fish in the tank too... Just shows you never can tell for sure.
Ive got 1 male and 5 females, and the male is a weird mix of white, brown, and red lol never full red but he spawns with the ladies often all the same. Of course because of the sanitizer incident, my 6 cherry barbs are left mostly to fully blind.
Another reason not to have aggressive fish--the blind ones don't stand a chance to avoid them.
These emperors though have the right amount of sass but keep it to themselves. And not even physical. Its a good healthy balance.
Oh, and when I got the Emperors in the mail they were quite faded. Photo taken during acclimation. I acclimate in a container and slowly add tank water to the container, drain it out and add more until its full tank water, then dump into a net then add them to the tank. Over the course of an hour or so