Years of my experiment brings me the conclusion that the panda coloration (or the tricolor as its side effect) is actually the blue coloration in metallic scale fish that undergoes demelanization process. That process can happen quickly in certain blue fish, turning it into a totally white fish or red and white one. But it can also happen slowly, even to the point of being halted forever, producing the beautiful panda / tricolor goldfish.

Recently, since 2018, breeders from Thailand storm the market with panda / tricolor oranda which seems to be strong in its coloration. I acquired some and breed them to see if they conformed to my understanding. And what did I find?

The offspring were not blue in color!

They were grey just like the common metallic goldfish!

I raised them to see if they will become panda like their parents. And yes, with mix results, I got several decent panda oranda. The results consist of grey (which does not seem to turn into black nor panda), black, panda, tricolor, and some who loses the melanin totally.

Here are some of the results that I raised until maturity:

So, panda does not come from blue fish only. My previous conclusion was wrong. I still does not know how the grey fish can become panda, since the common grey fish (red white fish) cannot do so. Actually, I experience this once a long time ago. But I dismiss it as an exception. Perhaps next time I can find my documentation and write about it. For now, I must humbly admit that there are panda color that does not come from blue fish.