The single dorsal fin is well aft of center. Teeth are small and pointed on both jaws.
Eyes are rather small, as are scales.
The adipose fin on its back, near the tail, gives away the eulachon's membership in the taxonomic order Salmoniformes. Length to 9 inches. Two other species of smelt can be found in Washington. It is inaccessible most of the but can be found in limited dipnet fisheries in Cedar River. Eulachon spend most of their life in the inshore waters of Pacific Ocean.