Thank you, Nina. Very interesting. I grew up catching and eating greyling in the Yukon (which does have clear and clean, cold lakes and streams) and while it was delicious, it was ubiquitous up there (and I was young and naïve) so I guess I didn't 'appreciate' its 'thyme-ly' nuances till now. The first fish I ever caught as a kid was a greyling.
The final dish looks amazing. Wish I had been there to try it. I am sure char (which I also love) works just as well as greyling.