An oddball natural lighting question...

Ok, so I have a 125 in my living room with a western exposure so it gets late sun. My wife noticed how beautiful the fish were as they swam in the few beams of sunlight that get through the glass tops. When she asked why the blacked back I told her in this case tons of sunlight can promote unsightly algae, she suggested just a 2-3" hole(in the paint) placed strategically would give a slow moving spotlight effect with change in angle of the sun...anybody ever done or heard of this as an intentional technique?

TFP

Hmm, sounds interesting. I've tried using spot lighting with small halides and such. But never with natural lighting. Sounds neat if pulled off correctly. At certain times of the day and or year you would have different illumination/highlights. I like the idea.

Went ahead and did it knowing it's easy enough to repaint black if it blows. Will report tonight after a full day's sun and observation.

TFP