Drawing upon the misinformation stories debunked by the three accredited fact-checking platforms in Spain, a content analysis of all the hoaxes (N = 292) bound to the Covid-19 pandemic is performed, over the first month of the state of alarm decreed by the Spanish Government (March 14th, 2020 - April 13th, 2020). The study shows that the hoaxes about the coronavirus were disseminated mainly on social networks and, among them, especially in closed ones, such as the WhatsApp mobile messaging application. It also detects the most frequent formal and content peculiarities of misinformation. The results reveal that the pandemic, in addition to generating a large number of hoaxes on health and science, also led to the dissemination of many political fake news. The formats, sources and territories of origin of the hoaxes are also explored. Beyond the empirical results, this study makes theoretical contributions in the framework of the emerging studies on information disorders. Specifically, it provides a definition of hoax, as well as a typology in which four main types are identified: joke, exaggeration, decontextualization and deception. Based on these four types, a 'hoax severity diagram' is proposed.