Thanks for the fast reply!
Yes, I live in Brazil and I'm not quite sure of the tree's name in english....
Hey, welcome to the forum!
I am Brazilian also, and I've been growing Amoreiras (Black Mulberry) from seed with great success.
Mine are like yours, but no black spots.
Did you repot it recently? Use a general insecticide like Jimmy just to be sure.
But... By the looks of your leaves, these black spots look like some sort of sediment left by the watering, no?