I think you catch more fish with the dark lines. I notice how well you can see someone casting a bright line through the air over the water and that can’t be good. I don’t want anyone seeing me including the fish. I use a dull light green for nymphing so I can see the drifts very well and I’m targeting fish on the bottom. I use a dark green or a mustard line for anything looking up.

I used to use light gray floating and dark gray sink but the lines I like don’t come in that color anymore so that’s another issue. It use to be simple.