hmm.... couln't tell ya... I've fished for a couple different things on a Fly rod but never have fished for kokes. My suggestions would be SMALL Egg Sucking leaches WITH VERY bright colors and probably some flash in the tail, or small colorful nymph or scud patterns... they are very touchy and it might be hard to do!! But a 14" koke on a fly rod sure would be fun!! Just remeber kokanee will also attack on aggresion not as an actual feeding pattern so bigger flies like BRIGHT leaches may unleash the agressive side of a koke! And also try bright colors like orange red and Fl. Green
~matt

PS
Lemme know how things go if you try it!
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Tight Lines smile