Think that's a pic of the fish in it's natural colors...can be prone to skin parasites, the gold is a substance the fish produces as a form of protection.
i'm pretty sure that it isnt that fish, the fish it very silver with a black spot at the base of its tail & has no noticable marking on the fins. Ours is prob a baby but its only about 2cms long
I'm still convinced it's a brass tetra....like I said, the pic in the link above is it's natural coloring.
If u run a search on H. rodwayi or brass/gold tetra, I'd be surprised if u didn't run across a pic that looked like ur fish.