Violet (purple) is right next to UV in the color spectrum. As far as light goes, UV is only special because it's outside the range of human vision. If our eyes had photo detectors for UV wavelengths, they would just be another color.
I'd guess that fish that react to UV reflectance will also react to purple. It's like bright green and chartreuse. They are close in color, so sometimes the fish will accept either.
of course, nothing is always true in fishing.
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