This hard sheath, however, is absent in juvenile chiselmouth. Pharyngeal teeth are stout and hooked. The dorsal fin on A.alutaceus begins behind the origin of the pelvic fin, and generally has ten fin rays. The caudal fin is distinctly forked, and the anal fin's origin is behind the termination of the dorsal fin. The number of fin rays is usually nine, and occasionally ten.
Pelvic fins are well developed, and rather narrow, with nine to ten fin rays.
The peritoneum in intensely black and the intestine is at least twice the body length. The overall coloration of the chiselmouth is rather bland. There is a vague black spot on the caudal fin in juvenile A.alutaceus . The oldest fossils of the cyprinidea family were found in Asia, and date back to the Eocene. The earliest fossils from North America and Europe are from the Oligocene age.