The U.S. Fish and Wildlife Service has recommended that two species of fish should no longer be listed as threatened on the Endangered Species Act due to a classification error.
In October 2015, the service proposed adding the roundtail chub and the headwater chub to the Endangered Species list but in September 2016, it learned that the headwater chub, the roundtail chub and the Gila chub are all actually the same species. The species will now be classified as roundtail chub (Gila robusta).
The Gila chub is already on the Endangered Species List and it will remain there, but previous  recommendations to add the roundtail chub and headwater chub will be dropped.

“Because the entities previously proposed for listing are no longer recognized as species, we have determined that they are not listable entities and are withdrawing our proposed ruling,” the U.S. Fish and Wildlife Service said in a press release Monday.
The American Fisheries Society and the American Society of Ichthyologists and Herpetologists Joint Committee on the Names of Fishes, said the reason for the mix-up in identification is because the fish vary slightly in appearance depending on what watershed they live in.
The Arizona Game and Fish Department applauded the decision.
“The Joint Committee’s determination last year, along with today’s U.S. Fish and Wildlife Service decision, is a huge win for chub and for those who manage and conserve chub in the lower Colorado River basin,” said Chris Cantrell, aquatic wildlife chief for Arizona Game and Fish. “The taxonomic history of this species has been debated for decades, which has influenced our management strategies and our ability to implement conservation on a range-wide basis. The decision will open doors to more opportunities to protect and conserve chub in Arizona.”