North America


Chasmistes cujus


  • Physical barriers in water habitat
  • Low water conditions
  • Declining water quality

Cui-ui is a plankton-feeding stream spawner that can only be found in Pyramid Lake, Nevada. This large sucker fish, which matures at eight to 12 years of age and can live up to 40 years old, is one of the three from the Chasmistes genus. Its main breeding ground is the Truckee River, the only perennial tributary of Pyramid Lake.

Construction of water diversion channels, dams, and blocking devices within and around the water habitat has greatly affected the Cui-ui’s way of life. Siltation pollutes the water and decreases the availability of food sources. Surface water elevation has dropped way below its normal rate. This makes the Cui-ui young vulnerable to being eaten by non-native fish species while the adults have difficulty reaching the spawning grounds except during high flow years.