i have a RBPacu and a large knife fish and a big pleco. no problems yet with the exception of the occasional sprawl but no damage. My Pbass area bit bigger though.
And I have mine with some bigger aros and they do well with eachother.
You maybe some dats or anything not too aggressive that can't fit in the peacock bass' mouth. Ie. Dats, Pacus, Maybe even some rays.