The U.S. Fish and Wildlife Service said Tuesday it plans to propose reclassifying a rare Colorado River Basin fish called the razorback sucker from endangered to threatened status after a multiyear and multistate effort throughout the Southwestern U.S. to replenish its populations. A proposed formal relisting, to be published Wednesday in the Federal Register, would classify the fish as no longer on the brink of extinction. But it would require continued management of the razorback’s survival in the Colorado River and several key tributaries. The Fish and Wildlife Service first said it would recommend the change in 2018.