The sagitta morphological development of laboratory cultured Hypophthalmichthys molitrix,Aristich-thys nobilis,and Ctenopharyngodon idellus during the postembryonic development stage was studied.Stepwise discriminant analysis was used to distinguish these three species based on the day ages after hatching,sagitta shapes,postembryonic development stages and different body length groups by elliptical Fourier analysis of oto-lith morphology.The results showed that the total classification success(%) all increased gradually.The classifi-cation success was 79.79% on the fourth day after hatching,above 90% on the tenth day after hatching,and up to 100% after 18 days.The classification success was below 90% before the chordal tip lifting stage and above 95% after the two chamber air bladder stage.According to the sagitta morphology,the classification success at round and near round stages was 61% and 81%,respectively,but was over 90% after the oval stage.The classification success based on different body length groups was initially over 90%.So,if only compared by classification suc-cess,the approach based on different body length groups performed the best.The approach based on sagitta mor-phology and postembryonic development stages was more general in use.