Nothing in there states that fish cannot see blue. And we already know that most all colors are diluted with depth, lack of light, or less than clear water conditions ... and some are seen as grey, while others are seen as black.
I don't fish "gin clear" water, and my success rate with blue/char lures has been exceptional over the years. Whether it's the contrast between the blue & chartreuse, or the silhouette of the bait against the water's surface, sky, or underwater background ... is insignificant to me, because I know it works.
"G's" color choice has the contrast, motion, and water pressure disturbance factors covered pretty well ... so even if the fish cannot "see" it as true blue in color, it still will elicit hits.
And I wouldn't be so bold as to go down to Weiss Lake & tell the guides and anglers there, that the Crappie can't see blue spectrum colors ... because I know for a fact that blue/blue/blue Jiffy Jigs can be hard to find on the shelf at times
(because they've all been bought up, because they work).
Ever hear of Dr Loren Hill ... creator of the Color-C-Lector ?? I had one of his first run units, back in the 1970's ... and quit using it and sold it, because it mostly told me to use the color I was already using .... BLUE. Specifically, blue/chartreuse (stained water) or green/char (muddy water). I'd already heard from "the man" himself, Bill Dance, that any color is a good color (for Bass) ... as long as it's blue/char
so why did I need a "color selector" to tell me what I already was using would be the most visible color at that depth & under those conditions
I even remember some "research" done on Bass, that stated they could distinguish between 11 shades of grey
IMHO ... we may never know what colors fish can see or not see, but it's extremely doubtful that we'll ever know what the fish perceives those colors to be.
... cp