I don't think I can agree with everything Marc has said. Whether a panda changes color or not has nothing to do with how much you pay for the fish, and is very much so a crap shoot. The more expensive fish tend to be larger, and a larger fish will have a greater chance of holding onto particolored patterns, but at the end of the day, there is no fixed genetic makeup for a panda goldfish. If you want truly stable bi or tricolor goldfish, you have to get into some of the new color varieties that have been developed from calico stock. Tricolors, kirin goldfish, and many of the crystal type colors have been shown to hold their patterning/color far better than any of the straight up metallic goldfish. Unfortunately, these fish tend to show a mix of colors, more like a brindle dog than the well defined patches of solid color one generally expects from a panda goldfish.