Ideas for mounting aquarium lights

[Scythanith]

If you don't mind putting two smallish holes in your roof you could suspend the whole thing on two pieces of aircraft cable. Paired with some adjustable anchors it would be infinitely adjustable. Make a clean looking aluminum rack to mount the two fixtures to, attach the cables to the rack. Voila, clean looking adjustable light rack. Also, you could change light fixtures whenever you wanted.