Please welcome Eyoyo Underwater Fishing Cameras.https://amzn.to/3siEgXn
They say the red color is exposed to be invisible under water because red is the first color to be absorbed. Red is visible 0'-30'. Orange 0'-45', yellow 0'-60', green 0'-80', blue 0'-100', purple 0'-120'. Something like that.
I used a red color cajun line and it seemed to scare the fish away. Presently I use a clear 15 pound flurocarbon line and am very happy with it. Doesn't stretch much at all, not much memory retention, holds good knots. Costs a little bit more but delivers. Recommended.
I still haven't figured out why they say fish can't see red line but they put red on jigs and lures so fish can see it