What A Fish Sees

I thought it was darn near impossible to tie these below size 16 as they are so busy.

I was going thru Livingston on a hunting trip a decade or two ago and stopped at Dan Bailey's to stretch my legs. I asked them if they had any in a size 18 and they replied 20's also. Said the tyers in the side area tied them for the store.

Never used them as they are in a display in my fly tying area.
I presume that you are talking midges here? Anything size 20 is too tiny for these old eyes. I can't see the eye of the hook nor the end of the leader.
Heck of a tough tie. Faster, broken water is batterer for me. :)

Old Man

Just an Old Man
I thought that also. but the size 18 and 20's eyes are just, just. You need a lighter leader as 5x doesn't fit the eyes to good. And if you get some that small, cut your tippet on the bias, slant. It will fit in the eye better. The sharp side will go into the eye easier. Found that out when my 5X didn't want to go in the eye.