On one of my ponds I included a glass panel to enable me to view the Koi from a distance.
I am actually surprised to see how seldom you get a glass panel on Koi ponds. The additional costs are minimal and apart from the fact that it looks nice, it is also very practical. Whenever there are problems with the fish, you can see it immediately. Very often, ulcers develop on the lower side of the fish. With a glass panel, you can diagnose a problem so much better, and you also spot the presence of external parasites like Anchor worm immediately.
You can also learn quite a lot from their bahaviour, by looking at them from another "point of view"
The colours do look nicer from the top, but to have an additional "point of view" it is great.
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Koi are not my whole life but make my life whole