Can I just clarify something regarding the great outdoors.
Granted there are some hot and sunny places.....I have been lucky to have been to Saudi Arabia, Oman, UAE, Yemen, Brazil, Argentina and India where cloudless blue skies and baking sun are quite frequent.
However there is maybe less than a handful of places that have totally cloudless blue skies and baking sun 365 days a year without fail.
What I am trying to say, and what seems to be misinterpreted, is that the lights supplied with an aquarium are extremely bright, piercing bright and they are relentless.
The sun moves in the sky...a bright aquarium light is fixed
As the sun moves it can throw shade via the landscape throughout the daylight hours, so there will always be a slither of shade in which fish can go to
An aquarium light stays put and does not give the same effect that the sun does, the fish have no peace from it, it is relentless, it doesn't get shaded by clouds, it doesn't dip behind landscape...it is there above them for as long as the human has it turned on......floating plants cannot replicate the sunrise or the sunset nor can they replicate a cloudy day...the light is full volume all the time.
Which is why swapping out to a light that can be dimmed or using theatrical film over the light can dial things down and make it more natural. If, like me, you have a remote controlled light that can be infinitely dimmed or brightened, then you can really go for the cloudy day, cloudless day, storm clouds...even a sunrise and sunset. By changing the light intensity and changing from a harsh white to a greyish light you can replicate closer and the fish react to that in incredible ways. The theatrical film give that effect ability cheaply and easily without replacing the entire light for one like mine.
Think of it as a human having a bright light shone direct at you compared to a warmer, softer light in the corner of the room...the light in your face is intimidating, it is uncomfortable whereas the warmer, softer light in the corner relaxes you and makes you feel comfortable and cozy.