Southern California’s unarmored three-spine stickleback has made headlines periodically, most recently over a lawsuit that was filed on Jan. 18 by the Center for Biological Diversity against the Trump Administration for allegedly failing to take measures to protect the endangered fish. What is the three-spine stickleback and what is going on with the fish? … The unarmored three-spine stickleback was listed as endangered in 1970 under the precursor to today’s Endangered Species Act. Critical habitat was proposed for the species by the U.S. Fish and Wildlife Service in 1980, but never designated.