That would be fine. As short a daytime as you want, but fish do need a night time, and some times these moonlights are too bright to be considered night.
Fish only need light to see to eat, and of course for you to enjoy the tank. Coralline algae that gives rock color can grow with very little light. Even ambient light from a nearby window could sustain it. If you were to mimic the natural day like you proposed, fish and rock will be fine.