Thanks for the info, Jan.

I was away, so I haven't caught the fish yet. But, the Tricide-Neo
arrived today. Should I still use that and if so, is that in place of
the salt dip?

I have the .3% water ready for the fish... when I catch it.

My salt dip info in my Koi Health & Disease book says 50 Tablespoons
to 5 Gal. for a max 7-10 min unless the fish is stressing/flipping
over, then move to quarantine, and repeat every 12 hours for 3 dips
total. Is that what you were thinking?

I'm hoping to catch the fish today using the "bird netting" method Joe
mentioned. I think that's the only way I'll ever get it.

The algae on the wound is gone, and the area is a lighter orange now.
The fish is still eating and active.