My sorority has about seven girls in it, and I've got four or five (they are stuck into the plants, so some are lower than others) floating plastic tumblers in there for them to hide in. They LOVE them. One or two will stake out a cup and they'll sleep/hang out in there since they're at the surface.
They don't look very natural...but the girls love them. If you get them in colors that match your plants or silk plants, they're not all that intrusive. You could probably find some in shades of green, and then they wouldn't be horribly unnatural looking with all your beautiful live plants. :)
Right now my sorority is only silk, but hopefully it'll be natural planted when I get around to it. :)
Oh, and the plants in this one are terrible...I wanted to know what big fluffy flowers would look like...and the answer is not good. At all. ;)
But, it's providing them with plenty of cover for the moment...until I can get them decorated with something much more appealing. ;)
Here are some pictures of the cups:
Oh, and I floated them in cups for a day before releasing them. Even though they'd seen each other for 2 weeks prior in their little holding "cells", there was still a small amount of chasing, nipping, and slashing until they chose a leader and got oriented to one another. Now they're pretty content to hang out *together* in big groups...so apparently they got over it. :)