what to add

Angels are delicate "community" cichlids that would probably be killed if the acar or any other large cichlid decided to atack it, so I would stick to a few smaller and peacefull cichlids, if you absolutely have to have another species of cichlid in there.

So, go with a pair or trio (trio=1male+2female, if you don't know what that is) of rams or cockatoo cichlids, and 6-8 bloodfins or rosy barbs (or any other similar and peacefull schooling fish), and then your finished stocking your tank.