Abstract: This paper reported the results of observing daily growth increments in the otoliths (sagitta) of the glass eels collected from river estuary of Liaodong Peninsula and elvers artificially reared.The mean diameters of otoliths of the glass eels end elvers were linear correlation to their body length.The mean daily growth increment in the otoliths of 12 glass eels was 146.3.From the daily increments,it was guessed that their spawning period could be 11-12 month.The observation results proved that there were transition zones (mark ring) in the otoliths of elvers lived in different conditions from estuary to fresh water.