Wallmart usually just sells "assorted african cichlids" you wont get a scientific name. I've seen zebs, peacocks, Labs, and varius mbuna species, once even what Im guessing was a butterkofri or frontosa. All in the same tank of course.
The fish in the photo doesn't look like a melanochromis species to me (kinda resembles some sort of copadichromis species, but wal-mart wouldn't have those, would they?).