I live in a high rise condo. The living room with the 2 fish tanks do not contain any natural sunlight. I am not a morlock our bedroom is practically one gigantic window.
Since I run the timed daytime lights (and airstones) only 7 hours daily the only time I can physically see the fish are one hour on the weekday after work and a short time on the weekends. Without the L.E.D.s the fish tanks are plain black unless you have the eyes of a cat or if you are The Predator.
The nighttime lights provide enjoyment for ME to actually see the fish. I bought them from Petsmart they are Marina Lights. You basically buy a base unit stored outside the tank and then you can purchase your own spotlights.
Red for nocturnal Blue is simulated moonlight White/neutral is a low level white light Green enhances a well planted tank, the tank will look like a painting more than a fish tank.
The fish are not bothered with the lights in fact it brings out a lot of their colors and I think submersible lights are a great way to showcase your tank if have them placed in a low light environment.
If my living room had alot of lights in it (and a windows) I probably would not even have made the purchase.