Sounds like your tank is already pretty stocked. If I remember correctly they get in the 10-12 in range. As for Agression I've had people strongly recommend I remove it or it will kill the JD due to similar look but so far it's not been an issue any more than any other cichlid would be. He's very territorial but his defense of that territory is limited to charging and gill flaring. So far he's been unwilling to lock jaws with my EBJD when he pokes his head into the bleekeri's cave.
