Red is the shortest visible wave length of light (next is infrared, infra means below, so below red = infrared) that humans can see so red light penetrates the least amount depth in water (besides infrared) around 15-20 ft. The fish seen the red jig because the fish was inches away from it and white light was reflecting red off the jig being perceived by the fish (even if it was a glow jig but light would be used to charge the glow through air instead of reflecting it through water, in the case of glow it's still emitting red light so depth doesn't really take part here, distance from the jig would better fit here) pink is also great for crappie. The white light penetrated the water, no matter the depth, and reflected the red of the jig. Just watch some deep sea extavating/exploration videos, if they turn on a light 2 miles below the surface, you can see the colors of what they are looking at. Light dispersion is relative to the light source. Back to your question, if you were to put the red window in your tank, and shine a light through it, even if the fish is color blind it will still be able to see the intensity of the light, no matter the color because you are diffusing white light through a red filter that is inches(?) away from your critter. The water is nowhere deep enough to for the red light to dissipate. But, using a red light would still be way less stressful than shining a bright white light in there. I use a 50 lumen white led flashlight from Wal-Mart for afterhour viewing, it's not bright enough to wake up my tiger barbs and I can still examine my tank pretty well. In your case, I would skip the red screen and just use a red light. I bought an Ozark Trail headlamp for ice fishing that has a 2-intensity spot light and a 2-intensity flood light that has a "red" mode. The red is to keep our eyes more adjusted to our night vision. It also keeps bugs out of your face and you are less visible (supposedly) to animals but in our situations of fish keeping, unless your white light is super bright, I don't think it really matters much. I'm far from an expert and I'm sure others have better info than I but these are the conclusions I've experienced. Cool topic to experiment with.