I cut out the bottom of a 100g vivarium, sewed the edges around the poles of the viv, sewed on a cheap waterfall shower curtain to the back of the outside mesh. Theres a plank and a big penguin 330 filter (was on our 90g ciclhid tank), so the filter basically jams the 100g viv onto the 55g fish tank, the plank provides a place for rocks and feeding/water dishes. The mesh and shower curtain are all connected back into the tank, so any drip system set up, misting, and cleaning runs all the excess water into the tank. The tank is heated to about 80, it contains our 3 polypterus (polypteri? heh), a red-tailed black shark, banded laoach and pleco. Possibly a spotted rapheal cat as well, but we never see him, so cant be to sure!! The full 4 feet of space is free for them to swim in lengthwise, but only about 6 inches wide, the branches on the right hand side extend down into the water and up onto land and intertwined with vines. Eventually I want to build them right into the corner, as the 55g is sitting kitty corner right now, but the bearded dragon needs a bigger home first. I'll get more baby pictures uploaded when I can get the hubby off the computer that has my ftp and photoshop, this one is just a little internet box. They are so cute! 
