Wild or Indian Almond Leaves (Terminalia Catappa) which are often used for rare and sensitive tropical fish. I personally use them for my tadpole teas as well as fish, as well as the eggs I may pull (tho I rarely do that at this point). The tannins in the leaves act as a sort of anti-bacterial, anti-fungal agent that keeps mouth fungus to a minimum and I get some nice happy froglets by using it (it helps the tadpoles not really the adults). I also feed tads the "skeletons" left after using the leaves for tadpole tea, epipedobates especially seem to love them. Oak leaves can be used in a similar fashion.
Oak leaves are also used for leaf litter in tanks since they are slow to decompose. I prefer leaf litter over moss since moss can be a pain to grow, leaf litter is where most of these frogs live anyways, makes them feel more secure, and for reasons already mentioned. Magnolia leaves work for this too. Almond leaves would as well, but they tend to be too expensive for people to just buy a box and toss in their tanks.