I use acrylic paint, and it is on the outside. If you want to change it, it comes off with a wet sponge, but its pretty good against normal wear n tare. It is on the long side of the tank. just grasses, tree branches and the such. The best part is, that with a light on for the frogs, the other side looks really cool. The paint is layered and it shows through really nicely. From the inside it looks a little plain, bu the frogs don't mind.

more branches and plants and grass growing.

added bigger rocks instead. do tadpoles need warm water?