Ahh... ok... didn't see this post before I replied to this guy's thread in the critique forum. If this is Shemma's fish (which seems highly likely) then it's descended from Jo Oakley's marbles which carried metallic. Several Melbourne breeders got fish from Jo at around the same time. The sibling spawns produced lots of solids, marbles, butterflies and cellophanes. I think this colour is very likely caused by one copy of the metallic gene affecting one of the underlying blue, steel, or turquoise but I'm not sure which one it is.