I think if you got some 10 inch wide pine from home depot, built a box with no top or bottom, added some 90 degree brackets to the inside corners, stained it to closely match, and sealed it with polyurethane. And then find at least 2 studs in the wall and bolted it to the wall with some substantial bolts....I think you could achieve an awesome floating canopy look. To my eye the best looking ones must have the power cords run through the wall, but a lot are using some kind of cord keeper to conceal the power to the lights.
That wouldn't be movable though, kinf of permanently attached to the wall, so it would have to allow you enough clearance to clean and rearrange. I wonder if you could do a 3 sided canopy with a top, then use bookshelf brackets....maybe you could slide the floating canopy on and off for maintenance, but have your lights suspended from the brackets? Something like this:
http://www.amazon.com/Stanley-Hardw...&qid=1462030006&sr=8-9&keywords=wall+brackets
I just don't know if a wall bracket would get your lights far enough away from the wall to be centered on your tank? Don't know how much weight a wall bracket like that can support either? However if you ever moved from the house or got rid of your tank....you could just put a shelf on it and pretend like it was always meant to be a little bookshelf there! (no patching drywall to cover bolt holes from idea #1 above)