You make good points Scat, why I don't believe its a lent is because of the thickness of the lateral line as it gets midway down the body. When I got my lents at 4-5 inches, they didn't have any lateral lines. Of course it could be a different collection point, and either way...its a nice looking fish with some sweet patterns on its side.
If the OP could post some more recent photos of the fish while its not stressed, we'd get a better ID.
If it is a lent, and the OP needs a partner for his fish...I've got a couple I need to get out of my tank so the dominant male and female can bond properly