For shallow water areas (under 6inches), I recommend java moss, java fern, anbia, all of which can/will grow out of the water with roots submerged. These are bog or shoreline plants that will work well with firebelly toads, and can stand up to the toads climbing on them. Also marimo (moss balls) (from Japan) can add dimension to the bottom of you tank, also standing up to your toads. As far as they being native from the same region as your particular fire belly toads... I am not sure, that part you will have to research