mine erythrinus is only at about 3.5" and is already trying to kill anything that walks by. He also attacks me when I have my hand in there. Should be a killer in no time. Just make him comfortable.
I agree Ery Ery are overall not an aggressive species. There may be a few exceptions but many can have tankmates as long as its not their same species. You have Lacerdae, Hoplias Malas, and a few other wolf fish species. These larger wolves are much more aggressvive than the Ery Ery but can have tankmates as long as certain guidelines are followed. The Aimara is the ULTIMATE KILLER WOLF, and thats NO JOKE...LOL. But if u want one....U NEED DEEP POCKETS, AND A HUGE TANK, AND HANDS MADE OF STEEL....LOL. Cichlids are more aggressive than wolves as far as being territorial and such but in a fight most cichlids dont possess the tools to take on a large wolf...GOOD LUCK...