I had a random thought.
You know how cameras have diffent filters to change the color of the picture?
Could you do that with a fish tank light?
You know how they hood has a glass window for the light?
Would like, colored seran wrap melt?
What about colored plastic of some caliber?

A piece of acrylic pianted with plastic paint(blue looks really nice) Is a good option for night lighting for your fish.I keep my lights on 24-7,so i needed a night time option.This provides a "moonlight" affect.