In that case you could go to a fabric store or even some Walmart's and purchase some of the green craft netting to ensure the safety of your fish. It's very cheap. You can cut holes for your plants and wrap the top of your tank or you can do a dome. People do something like this for outdoor ponds. You can do a DIY version cheap:
I have seen more decorative dome types where they put a little decoration on top like you might see on the end of a fancy curtain rod. I could find a pic but it's the same concept as the frame of a fancy bird cage there are several example but there are ones that have a rectangular base might an example for an aquarium:
or this lady did a more contemporary version you might adapt to your ripararium. You'd have to use something other than copper since it's toxic to some fish and invertabrates.
All of this has got me thinking I might try something like this in the future. I can hang my light from the ceiling and have the dome.