It is most definitely a Lates species.
Niloticus are mottled when very young in my very limited knowledge. This fish looks like it could be past that phase and has some size on it, albeit guesstimating size from such a photo can be grossly misleading.
The darkness or lightness of the coloration is a crucial function of lighting and photography. It can vary wildly and can be utterly unreliable, unless photographed professionally. But even so, the fish mood affects it too, often quite notably, and not always evenly, meaning the "mottleness" may appear or disappear depending on fish's mood.
What's harder to fake appears to be sheen.