something to add to my tank?

[biggisteve]

in my 55 i currently have a yellow top, an auratus and a pretty large blue zebra. the blue zebra has killed or beat up so that i had to move about 8 fish in the last year so that the tanks down to three, so frustrating

i'm looking for something to add to the tank, i assumed a large cichlid would be best so that everyone can hold their own. I had thought a green terror but the other forum says no way in hell cuzof the water conditions.
so any idea's of something to add is greatly apreciated

[Tightdog1]

if would definitely have to be something from africa. nothing from american because of the water conditions.