Just like a Canary used to let miners know that conditions in the mine were dangerous,
so does the Tancho Koi let Pond keepers know when water quality is not healthy for Pond Fish.
Look at the picture below.
Tancho Koi tend to develop red edges on their scales when the water quality in the pond starts to deteriorate.
Other Koi with white in their color do the same, but it usually takes much longer and much worse water quality before it shows.
It is, of course, best to test water quality regularly...but IF a Tancho Koi starts to look bad it is URGENT!
