Hi Don,thanks for the thumbs up on my stonework efforts. Suppose I do alright for an amateur. Theres a proper stone mason just did a job for an aquaintance of mine nearby,superb workmanship,just like your own. Beautifull work. As for the fish, Koi are nice but expensive and there are a lot of Heron in this area and aren't shy about visiting the tiniest pond in the most built up urbun area for a feed either. So I generally stick to goldfish. Lot of domestic cats around here too . I used to keep native river minnows and sticklebacks .Sticklebacks are fascinating wee fish to watch. I'll be starting to the new pond shortly.
As for the wood-in-cement tracklaying method,works fine as long as drainage is good. Otherwise frost-heave in winter could be problematic. 
