That'll be really healthy for your fish too.

Maybe a waterproof camera would work better. However, I'm inclined to believe my betta does see his reflection, unless he flares his gills and fins at memories.
Think of it as the way reflections work with windows. If it's nighttime, and your room lights are on, you can't see out. You see a reflection. People outside can see in. If lights are dim on both sides, you can see through both sides. In the daytime, you can always see out through windows, but if you turn the lights off, people outside can't see in... they see reflections. Would this really be different if you're in water rather than air? Honest inquiry.. I've never tested it.