Since there are probably over 100 blueish species from Lake Malawai, it may be hard to pin down.
My first impression is the Red Empress (or others in the genus Protomelas ) because it is commonly available in LFSs. And may be turned in as a large specimen because it got aggressive or hyper dominant in someones community tank
It also could be of the genus Copadichromis (there are over 20 blue hued species in the genus.
Or any number of others from the rift.