Skip to main content

Keeping Up with Koi Fads

By May 19, 2011October 28th, 2021Fish

Koi varieties are numerous, and each year new colors and patterns are cultivated – very similar to the way nurseries produce new varieties of flowers to pique the consumer’s interest and pocketbooks. Koi are no different. Each year sees a new fad, and some of these fad fish become mainstream, must-have collectibles. The asagi and shusui are two examples of koi that are somewhat new, but are now a great favorite among many hobbyists.

One Fish, Two Fish

Shusui and asagi are quite simply blue fish with bright red or orange markings. So when you see orange and blue fish, you know that you’re looking at some variety of shusui or asagi. There are specific pattern requirements that differentiate these two koi beauties, but the biggest difference between asagi and shusui is the scalation.


To picture a nice shusui, you would have a blue koi body, and paint a darker blue, almost black, row of brick-like scales down the center. To either side of this midline path, you paint a white stripe. On either side of the white, you put a uniform stripe of red. The fins and tail would be white with a sunburst of red in them.

The shusui has a soft, scaleless, pale-blue body. The belly will be bright orange (almost red) up to the lateral line. There should be an orderly row of armor (large) scales on the back running from the head back to the tail. These scales are a defining factor for the shusui. If the scales are rectangular and neat, even in size, and uniform, the fish is worth more than if the row of scales is uneven, doubled, or if the scales are wedged and triangular. To summarize, a blue body, red fins and cheeks, and a continuous stripe down the length of each side represent the ideal shusui.


The asagi is a scaled fish. Its body is dark blue with a beautiful, diagonal crisscrossing or fishnet pattern that is created by navy blue scales rimmed with pale blue. The belly up to the lateral line should be bright orange (or almost red). To be considered “perfect” the scalation should be impeccable with straight orderly rows of scales. The less wavy and the more complete the back is diamond-scaled in navy blue, the more the asagi is worth. To summarize, a blue body and red fins and cheeks represent the ideal asagi.

How They’re Patterned

In general, the pattern of shusui and asagi are not well served by the appearance of any orange on the fish in any location except the belly or the stripe on its back. A blotch of additional orange on the back of the fish may be very pretty but is not a favorable addition for judging. In some cases, especially the un-scaled shusui, the orange may come up the sides of the fish to encroach on the top of the fish, highlighting the row of scales in the case of the shusui. But opinions vary on how much orange a shusui or asagi should have as a young fish.

Normally the asagi and shusui would be viewed from the top and look like a stripe of dark blue, light blue, bordered on both sides by a band of orange. Sometimes the orange doesn’t come up the sides enough to be viewed from the top. Sometimes the pale blue blends with or borders on a whitish blue, and these fish are really pretty.

Buying a Good One

When you’re presented with a tank full of shusui and asagi to choose from, here’s a step-by-step decision making process.

Step One: Decide if you’re looking for shusui or asagi because the amount of red you’re looking for is different.

Step Two: Select the fish that are pale blue with orange bands up each side and visible from the top. Do not choose the all orange fish or the all blue fish.

Step Three: Remove all fish that have blotches of orange in their backs or on top of their heads. The orange color should be in a band or uniform stripe up each side, the length of the body, instead of a broken or blotchy pattern.

Step Four: Select shusui that have the row of scales from their head all the way back to the tail. Do not take a fish with red over this line of scales. The red should barely encroach on the top line of scales, but in fact should highlight a band of pale blue between the red and the navy blue row of scales. Select asagi that have less interference from red in the back, and the navy blue fishnet pattern is uniform all the way head to tail and don’t look smutty and black.

Step Five: Look at these fish from the side and select the ones that possess more orange from the belly-midline up the slightly above the lateral line, like they were swimming in orange paint and that’s how high they got colored.

Step Six: Now you have fish which are uniformly blue and red, neatly from front to back, with the red being visible from the top, and a proper row of scales from head to tail. The final cut is made by examining the rows of scales. For Shusui you want to see the most neat, rectangular scales with a little space between each scale, in a single row. For Asagi, look for the most distinct, straight rows of diagonal scales, clear white or blue between each navy blue scale is the most desirable. In both color patterns of fish, the tail, and the two pectoral fins should be shot through with a radiating sunburst of red or orange.

Aging Not So Gracefully

As shusui and asagi age, they lose their orange or red. When a shusui or asagi is more than 15 or 20 years old, it is not uncommon for them to be just a pale blue or even white fish with a few remnant navy blue scales on their backs. This is a sad thing because a young asagi or shusui is a thing of great beauty. But if you’ve had a fish for 15 to 20 years, you’ll cherish it for all the pleasure and memories it provided you.

This article originally posted by Aquascape