I have caught a BUNCH on bubble gum sluggos. It is a great piss em off type color. They hit it because they don't know what it is that has just invaded their space and they don't like it, not that they are hungry or wanting to feed. Using that at night will not get the same reaction. They can't tell the color anyway and are hopefully mobile and ready to feed.

You have low\no light conditions at night and hardly any of it is reflective. Natural colors and white bellies are not optimal. They can't see a white belly well from under it because there is no light reflecting in the water to show a contrast. But they will be able to easily make out a dark belly with a little surface light. They hit dark things at night because those are things they see more easily.