Re: Fly line color, does it matter?
The Trout and the Fly by Brian Clarke and John Goddard is one of the 3 or 4 most important books ever written about trout behavior as related to fly fishing.
In it there's a chapter where the reaction of trout to different colored lines is discussed.
As I remember, couple of points were that a white or light colored line flashing across the sky was as startling to the fish as a sudden flash of lighting would be to us, and that a darker line did not reflect the sky's light as readily.
Later in the chapter, they go on to discuss the difference different colored lines made on the water surface.
Hopefully most everyone here knows about a trout's "cone of vision" ,which is a subject too large to go into now, but outside the cone of vision is what Clarke and Goddard called the "mirror", where instead of being able to see up out of the water surface, all they can see is a reflection. Hence "the mirror".
To a trout, when a white or light colored fly line falls into this "mirror", it's very conspicuous and looks like what they called a giant crack, while a dark line was hardly noticed.
I wish I had the book with me so that I could quote it directly, but to answer the question, lighter colors especially white, spook fish while darker colors do not.
The simpler the outfit, the more skill it takes to manage it, and the more pleasure one gets in his achievements.” --- Horace Kephart