Volcanoes can be life-threatening for fish. A major eruption in 2011 in Chile, for instance, killed 4.5 million of them. Researchers have studied how lava flows, hot gases, and deadly debris can cause mass die-offs or even cut fish off from the sea in suddenly landlocked lakes. But few have been able to document in detail the grisly fates experienced by the unlucky fish that find themselves at the mercy of an angry volcano. That’s why when one erupted underwater off the coast of El Hierro in the Canary Islands for 150 days in late 2011 and early 2012, researchers including Ayoze Castro Alonso at the University of Las Palmas de Gran Canaria saw the perfect opportunity to study the intricacies of these piscine casualties.