One observation I have made is that if you are fishing a floating or shallow running plug then the belly colour is more important. The reverse is the case for deep divers.
I agree completely with the rest of your comments, but do not do so ‘completely’ with this one. Is this from personal experience or are you quoting a theory?
I have read this theory in books before and do not agree with it completely. A theory that I do sort of agree more with is a Black underbelly ‘IF’ fish are looking from down at a lure above. Again this only assists visibility.
If you look at bait fish, the under bellies of a baitfish (for that matter most fish) are pretty pale in comparison to the rest for the body, and if you will observe lure manufacturers who make lures especially the ones that look more fishlike copy this colour distribution.
In my experience, if a fish is resting on the bottom it is doing just that, resting, and will very rarely strike a lure at the top. Most of the ambush predators that I have taken on lures, take lures from behind something a rock or whatever and wait for the fish to swim past, maybe slightly below the fish.
Please do not misunderstand me guys. I just want a meaningful discussion coming out of this post so that each one of us is helped by another’s experience.
Neil, how many other colours have you tried on Barra and Threadfin besides what you mentioned? I have found pale yellow/greens to work best on Barra, and have not caught a Threadfin for such a long time that when I caught the last one I had all silver spoons/homemade plugs…maybe 2 real precious cosmetic lures that were mostly show pieces in a tackle box