MAMMOTH LAKES, Calif.— The Center for Biological Diversity sued the U.S. Fish and Wildlife Service today for failing to finalize Endangered Species Act protections for the Long Valley speckled dace, a rare hot spring-dwelling minnow.

“Our lawsuit aims to save one of the rarest fish in America, which the Trump administration seems content to let slip away,” said Patrick Donnelly, the Center’s Great Basin director. “When an animal like the Long Valley speckled dace is this close to the brink, looking the other way is a choice to relegate it to extinction. That’s reprehensible and illegal.”

The U.S. Fish and Wildlife Service missed a legally required deadline to finalize protections after proposing to list the fish as endangered in 2024. The only known stable population consists of a few hundred fish living in an artificial pond at a managed refuge in Inyo County, outside the species’ historical range.

The fish once inhabited Hot Creek and other warm springs throughout the Long Valley volcanic caldera east of Mammoth Lakes in Mono County, California. Over decades, geothermal energy development, water diversions and groundwater pumping altered the region's hydrology, reducing flows and drying up many springs and wetlands the fish depended on.

The last known wild population survived at Whitmore Hot Springs, where the dace occupied an alkali marsh fed by the outflow of a public swimming pool. There, the fish faced threats from chlorine contamination and reduced water flows. Recent surveys found only a few remaining dace, raising concerns that the species could disappear from the wild.

“Every day the Trump administration waits to grant protections is another day the Long Valley speckled dace loses ground in its fight for survival, and every delay makes recovery harder,” said Donnelly.

Today’s lawsuit was filed in the U.S. District Court for the Eastern District of California.

The Trump administration has not protected a single new U.S. species under the Endangered Species Act during its second term. It is the first administration since 1981 to complete its first year without listing a species for protection. More than 400 animals and plants across the country are currently awaiting overdue protection decisions under the Endangered Species Act.