Hm, never heard of spanish fado, think it was the melancholy part of flamenco.
Fado was "born" in the Mouraria, which is a part from Lisbon, and was very polical at the Salazar Era. Nowadays it's about unfulfilled Love, homesickness, and other melancholic themes. But it can also be very funny.
I'm surprised, that you've never heard of it, Haiducci ! It's very popular.