JR: Your catalog of photos is amazing! ... and that 59F data is very notable. [During a "serious" cold spell my water can get that low!
... for a couple of days, maybe.] I hope nobody is misled by the old observation. I think it may give insight on the very different roots of Showa, but Showa today are not much like those of 20 years ago. Off-hand comments on such matters do not deserve much attention. Since this observation came from a koikeeper with wide exposure in his day, I'll tuck it away as an idea worth having in mind as I look at koi. It does seem to me that around Florida koikeepers have greater success with maintaining Sumi quality than Hi quality. I tend to think that it is the silica sand soils that bring out Sumi despite heat, but no doubt on my own koi the cooler temps of winter coincide with Sumi becoming deeper. I'm not ready to draw definite conclusions, however. So much that is written is based on koikeeping in Japan and cool climates, and so little on warm climates, I think there is a great deal to be learned by warm climate koikeepers.
Bekko: I'm sure there are old blood Showa still around in Niigata, even with the quakes. But, I'm not so sure you really want them. If you go through old photography of show winners in the period 20-30 years ago, the best Showa are not close to the best to be seen today ... all that Kohaku and Sanke crossing really has improved the variety. I'd say it is very likely that any koikeeper who can afford a pond could easily purchase koi today equal to the best koi of 25 years ago, but might not want to take up space with them.
Hudi: Please explain your comment. Do you find Showa develop better in Malaysia than Kohaku and Sanke? How about Utsurimono in general? Your experience on this today would be very interesting.