But I must admit I make my whole bread & butter living in fly fishing (guiding and writing about it) with three knots. A nail knot, to tie a line to a leader. A surgeon's knot (4 turn), for tippet to tippet, or leader to tippet. And an improved clinch knot to tie on flies. That's about it. There are two other knots I sometimes tie... a perfection loop, for making loop-to-loop connections, and once in a while, a Costa Rica knot for tying a loop connection to large streamers. I'll also use an arbor knot to start spooling up a reel with backing.