Mesh would work well - but just remember to get something to cover the bulbs other wise the light will just go everywhere. Like a lamp with no shade 


/cgi.ebay.co.uk/CLASSICA-LUMINAIRE-T8-1500MM-2-X36w-OTL-LIGHT-/200555376694?pt=UK_Pet_Supplies_Fish&hash=item2eb2083036&clk_rvr_id=239571248061they do hold the shape of the aquarium so without them the aquarium may start to bow slightly.