The Electric Blue Johanni is such a gorgeous cichlid. I love mine to death, but I learned the hard way that I could have only one male. They are aggressive toward their own species in most cases. There are always exceptions to the rule, though. Mine is now in my 125 gal show tank with one EBJ female and several other species that are larger than him. Now that he's not king of the tank any longer, his aggressiveness has subsided.
mine is very agressive, he lives with my 9 cons (which will have a new home in few days) and 1 oscar. my cons teached him he was no longer boss if the tank i have over 100 convict babies and my johani doesn't dare to go close to them. he knows better!!