I think your biggest concern would be the growth rate of peacock bass. Considering that they will grow about an inch a month until they are 12", I would be a little concerned about the dats, but otherwise I think you would be alright.
I have two monocs and they don't really bother my other tankmates. They are currently housed with a silver aro, an RTC, a TSN and a royal clown knife. As long as something won't fit in their mouths, tehy are typically very peaceful.