I'm going to disagree based on the history of this tank. We have a Tinfoil Barb, a Parrot Cichlid, and 2 African Mbuna. This sounds like box store stocking and that usually doesn't include these species. I'm guessing Zebra mutt. Probably a fine community Mbuna, but not a purebred.
Blue Zebra.. Top fin turns black or white. Yours is white from what I can see right? I have one right now with a black fin... I've also seen them called Johanni cichlids. Most likely out of a mixed tank...