Funny to say, especially coming from Petco, but I think it looks like Tyrannochromis sp. It does not match any pattern of any Nimbochromis sp. Could be either T. macrostoma or T. maculiceps I think.
I'd say fusco to but there is a very small part of me that also says no to being a fusco. Maybe it is in between colors, and doesn't have the camo. pattern because of that. But usually they have a blueish to teal type coloring.
Funny to say, especially coming from Petco, but I think it looks like Tyrannochromis sp. It does not match any pattern of any Nimbochromis sp. Could be either T. macrostoma or T. maculiceps I think.