The Asagi is one of the oldest varieties of Koi to be developed with consistency. It is one of only three breeds of Koi that is blue and stays blue as it matures (if it is a decent quality one). It is a non metallic variety, and as such the pec fins are clear and/or can have some orange or red in them. The back is a pale blue that runs down to the lateral line of the fish (center line of the side of the fish). The reticulation of the scales on the back have a flat black center color to each scale, and no scales should be misaligned. From the lateral line down to the belly the fish it can be either red, orange,(or white in young fish). The red or orange can and usually does develop over time and at varied rates from fish to fish. It is one of the few varieties of Koi that this can happen.
The name Asagi translate to "setting sun" as the orange that develops on the sides (the sun), combined with the blue back (the sky) resembles a sunset . The fins and cheeks usually have orange as well, and sometimes some on the dorsal fin base.
A Good Asagi
When judging Asagi the first and foremost is that the reticulation be consistent and balanced with no scales looking out of place. Each scale on the back should have a flat black center color that is bordered in blue. This resembles a fish net pattern. The orange on the sides should not rise above the lateral line, and should be straight and crisp on the upper edge along the lateral line.
Understand however that in picking a good young Asagi you look for the blue to be very pale in color, and that the flat black reticulation may be very difficult to see if at all. The same holds true with the orange on the sides of the fish as this will develop over time and at varied rates from fish to fish. In young fish if the orange on the sides (the sunset) is too strong in color, there is a good chance that it will migrate up to and over onto the back of the fish. This would make it a lower grade fish for sure, but some can be striking to look at if balance still retains. Also in young fish less than 6" you want to see a whitish tipped nose area of the head. As it matures the head will then be clean white or pale blue. You do not want to see a dark head on any age Asagi.
So in picking a young Asagi look for at least signs of the black fish net pattern on the back, pale blue color, a white tipped nose area, and at least some orange on the cheeks or fins. The pale blue tone is critical because if it is too blue when young, it will end up looking more black when it matures. This is the number one mistake people make in judging young Asagi. There is a good chance that the orange sides will develop in time if you see even a speck of orange there.