Thankfully, I did catch a glance of my youngest koi a short while ago. I'm afraid the blue is probably gone, and hopefully the larger yellow is just hiding.
I have lots of pinwheels around the pond, and other moving windchimes, etc, which I think look a bit cheesy, but I have them anyway because of the heron. Also plants on the shelves that I hoped would help deter. As soon as it stops raining, I am going to string fishline across once again - it came down during winter, but then we won't be able to get into the pond to deadhead the numerous water lily pads unfortunately.
As for trying to shoot it with anything at all, it usually comes when we are not here, of course. When we do see it, it's usually too late and it's flying off.
I understand your need for netting, but I just feel that it takes the joy out of ponding altogether. I guess I will resort back to the cheapo 27 cent feeder fish if it comes to that. Most of my 6 inch goldies started out that way a few years ago, but they are the ones that are desirable to the heron now.
HUMPH! :-P