Have you considered adding dither fish? They will make the cichlids feel more comfortable, possibly help disperse aggression, and provide activity and color for your tank. Tiger barbs come to mind as good tankmates- you can find them in the regular, green, or albino variety and all are the same species (and will therefore school together in a mixed group if you like). Try a group of 6-8 if this appeals to you. Good luck!
a parrot aggressive? Right if ya say so. they get aggro when they are spawning just like anything else. but it will be able to hold its own against the jewel and the convict. 1 male and 1 female yes they will be aggressive but 2 males no spawning = no aggro. and rule #1 more fish less aggression in the tank. with cichlids overcrowding is a good thing just remember to over filter as well.. just stick to the same community's and everything should be ok.