No, Fontaines D.C. is not a goth band, because they play Post-Punk, while goth music consists of Gothic Rock and its derived genres, like Deathrock, Darkwave, Ethereal Wave, and Coldwave.

However, they do have a significant goth influence and even have some goth songs in their repertoire, like "Bloomsday", "Roman Holiday", and "I Love You".

If you want to dive into the goth music scene, some of the bands that might appeal to you if you enjoy Fontaines D.C. are Pink Turns Blue and The Cure.