To put it bluntly, we use R,G,B because those are the photoreceptors in our eyes. Our R,G,B LEDs are tuned for maximum effectiveness on our photoreceptor cells

To put it bluntly, we use R,G,B because those are the photoreceptors in our eyes. Our R,G,B LEDs are tuned for maximum effectiveness on our photoreceptor cells [1]. Red photoreceptors are probably not very useful for sea fish as red is easily scattered in water. [1]: https://en.wikipedia.org/wiki/Cone_cell#Types https://en.wikipedia.org/wiki/Cone_cell#Types