In May through August 2006, two pupfish from Devils Hole and five from the Hoover Dam Refuge were transferred to a Las Vegas Strip casino aquarium at Mandalay Bay with the hope of understanding how to breed the species in aquaria. Propagation efforts at Mandalay Bay failed, and by April 2007 all individuals had died or been transferred. Also in 2006, six younger pupfish were moved from Devils Hole to the Willow Beach National Fish Hatchery in Arizona. Additionally, the eighteen remaining individuals from the Hoover Dam refuge were moved to Willow Beach. While early breeding efforts appeared successful and four larvae survived to adulthood, all individuals had died by December 2006, possibly from a form of leukemia.