Females are somewhat faster growing than males.
Although this species is short-lived, growth patterns on some butterfish otoliths are quite complex. Annuli may be very difficult to identify due to formation of checks within opaque zones and split or diffuse hyaline zones. Otoliths are examined by viewing the distal surface in ethyl alcohol against a dark background using reflected light at a magnification of 15x. Therefore, the first annulus, completely formed by the end of the first spring after hatching, is some distance away from the nucleus of the otolith. By convention, a birthdate of 1 January is used.