I'm thinking P. Elongatus Chailos (sp?). I got 2 mbuna from the various mbuna tank at my LFS. They looked identical as juveniles, but over time 1 started to turn yellow and the other is still dark blue.
If it is a Chailosi, then I would say it must be a female. This fish belongs to the sp."elongate" and they, male especially, all tend to have the colour go from the body into the tail. In other words the stripes stop at around the anal fin. Females tend to have the stripes all the way through the body. I breed with these, my main female has just given me around 50-60 fry and is carrying again, and all my male fry look the way I have described the male.
Will look at trying to get a good shot of my male.
It might have P. elongatus in it, but it's is not a pure specimen.
I would suspect a M. lombardoi hybrid, due to description. Possibly a M. lombaroi x P. elongatus Likoma.