If that is a Dempsey, it doesn't look skinny to me so much as lacking the "I just ate everything in the tank that I could fit in my mouth" stomach bulge that is popular with that fish. It looks young to me.
I bred Jack Dempseys 30-35 years ago and while they looked awesome with their breeding colors, the electric blues that are available today are simply stunning. I think brightly colored discus (which I've also bred) might be the prettiest FW fish but the electric blue JDs come close.