This river here in the middle of the Amazonia is known as Arrapiúns, yet above the waterfall, the river has no name.

One day our forefathers saw a frog, and on his back there was written, Aruã. And since the river beneath the waterfall was already called Arrapiúns, they named the river above the rapids, Aruã, due to the frog. The river is still called this today.
This frog came from here, from the Amazonia.

We no longer know the meaning of the word, Aruã, but it is an old Red Indian name.