I read recently about the dangers of handling fish (to return them), in an article by the Salmon and Trout Conservation organisation (in Wild Fish 2021), and realised how damaging it can be to handle a fish, no matter how carefully you do it. They recommended a technique for releasing fish using forceps without touching the fish called non-contact release. This YouTube video shows how it is done.
The video shows the technique on big sea trout or salmon, but today I tried it on 3 small Brownies that I'd caught on my favourite #18 dry fly, and it worked every time.
Basically, you hold the line a foot or so above the fish, and slide the forceps down until you're gripping the base of the fly, then simply twist the fly to slide the hook out. I didn't have to touch the fish at all, and they all swam off very quickly.
Of course it helps if you're using barbless hooks, but why would you use anything else?
I strongly recommend that you try this technique - it was much easier than I expected, and would be particularly good for Grayling and Browns. It may not work on some fish, but I'll be trying to use it every time in future.