Guanine is the substance responsible to produce the shiny metallic look in the scale of goldfish. When the guanine is absent, we will have the transparent colored goldfish such as sakura and calico. In goldfish world, as far as we know the guanine is found in the scale. It is sometimes found in the gill also. But I have never heard anyone mention about the presence of guanine in the fins. The fins of goldfish is commonly found in its transparent state. Lately, as I was observing my fishes, I noticed a certain yellow fish that have unusual deposit of guanine in its pelvic fins. This is the picture I take this morning:

It is quite shiny compared to others such as this:

I begin to recall that koi has a variety called ogon, which has shiny fins. I begin to suspect that what makes ogon koi have shiny fins is the abundance of guanine level in its fin. And my mind keep thinking whether it is possible to create ogon like goldfish, that is the goldfish with shiny metallic fins. An ogon goldfish might look like this photoshop image below. Notice the unusual shine in the fins. It will be very eye-catching in the tank. (Sorry for the low quality image).

The yellow fish I have makes me think that this is possible. It is just that nobody has tried this. It will be a tedious project though. Maybe we will need to select fishes that have more than usual guanine deposit in its fins and use them as parent fishes. Maybe this need to be done for many generation through selective breeding until a truly ogon goldfish is created. It will be a long journey. But this will create a new kind of goldfish! Does anybody want to take this challenge?