The ones that you can pick up at Home Depot, Lowes, Franks, and so on do get too large for smaller tanks. They can get very tall and very wide, but aen't the fastest grower in my experience. A couple cool things about them is that they will flower in tanks, they have nice broad leaves for eggs laying, they will support a frogs weight, and that they can grow completly in the water (roots submerged). So they are neat plants, but do get rather big. I think they same could be said about Peace Lilies. I am interested in trying some of the different Anthuriums out there, ones that supposedly will do great in terrarums and are smaller.