So there's this weird thing with the name of the writer who first introduced the Mirror Fish to the western world. di Giovanni uses Fontecchio. Hurley uses Zallinger. So I dug up a pdf of the Spanish publication of Book of Imaginary Beings. El Libros de los Seres Imaginarios. "Animales de los Espejos" is the title of the chapter in question. The original text uses the name Zallinger. So where did Fontecchio come from?
Both Zallinger and Fontecchio were part of the La Compañía de Jesús, which is...okay, I'm just going to admit that I don't know Spanish. Anyway, La Compañía de Jesús, is Society of Jesus in English.
Updates as they arise.