An excellent and deeply researched article on the MidCurrent site will provide answers to any and all questions you might have on the relevance of Ultraviolet light to fishing.
The money shot:
“He found that ultraviolet photographs of trout food looked “pretty much exactly the same as any other black and white photographs of the same subject.” He also went on to say that this was not surprising: “… trout food insects just simply don’t possess strong UV-reflectance patterns, and that trout are not likely to identify their food by looking for UV reflectance”.
… But for fly fishers, there seems to be no reason to elevate this trait to any significant status. For trout and a number of other species we target, ultraviolet-sensitive vision does not seem to be a component of the adult fish’s behavior, and it is especially unlikely to be an important part of the way they locate and identify their food.”