Sometimes you can get away with company for an agressive fish by putting faster smaller fish in there - it avoids a head to head fight scenario. Not always fun for the small fish, but some are better than others at it.
I used to have Blue Acara in with a mean *** Midas, but the Acara would latch onto his tail (the end without the teeth) and just stay on point, always turning faster than the Midas could. Eventually the Midas would get dizzy, and the Acara would swim off grinning.