The chiselmouth (Acrocheilus alutaceus) is an unusual cyprinid fish of western North America. It is named for the sharp hard plate on its lower jaw, which is used to scrape rocks for algae. It is the sole member of the monotypic genus Acrocheilus and is a close relative of the Gila western chubs.The chiselmouth's body plan generally follows the standard cyprinid form, generally elongated and slightly compressed.