I like the plastic chicken fence. It is really small plastic net-like material. It needs a frame to be built, but it looks very smooth and doesn't block much light at all. I've been lucky so far with only one SW fish in seven years taken the trip, but on my current build I'm definately looking at using it.
I saw it on one of the reefkeeping mag tank of the months six or eight months back.
~300-Gallon in-wall low light fresh water system~
After 10 years, I am taking a break from salt water keeping