i have about the wierdest set up for my growout 55 gallon...
i have a jag- 4 inches
a nic- 4inches
firemouth- 3 inches
frontosa- 3 inches
and a jack dempsy- 4 inches
i have never seen them fight...they all eat fine together no aggression when feeding, i will throw some roseys in once and a while and the jag will get the majority, but they all seem to live well together for now. i think fish keeping is more of a trial and error sometimes, not everyones fish are the same, just go with what you think and test it out, but dont let it get too ugly or u might have some dead fishies.