WOW...Amazing colors. You should really embrace its natural colors instead of want it to turn into a super shinny fish. That yellow tail coloring is amazing and not all juvenile silver aros come in that color. Nor do they all turn the same color when they fully matured. However since you really like the silver shine, you should stay away from color enhancing foods. A buddy of mine had an arow that looks just like yours when it was small. He fed it raw shrimp at about that size everyday. It got to 32 inches before it died, but as a result of the shrimp diet, all its natural colors faded away and it turned very very silver and shinny, almost platinum-like. In my opinion, the most beautiful silver arowanas are the ones that reflect the colors of those from the wild.