Larimichthys crocea). We observed daily periodicity in growth increment formation in the sagittal otoliths. The first daily increment was formed 2 days after hatching (dah), corresponding to the time of first feeding. The sagittas were uring the yolk-sac larval and pre-flexion larval stages, on the long Following this, the sagitta became ellipsoidin shape during the post-flexion larval stage. During the early juvenile stage, the first secondary primordium began to form between 29−39 dah (32±0.39), corresponding to the timing of from larvae to juvenile. The number of secondary primordium ranged from 5 to 7 in 47–­­78-day-old juveniles, and the secondary growth zone (SGZ) structure”. During this stage, the sagittas were nearly peltate in shape. The radius () of the sagitta was significantly and linearly related to standard length (S) (b), calculated based on the width of the daily increment on the sagitta of juveniles, were significantly and linearly related to the time of formation of the first secondary primordium ((<0.01). This suggests that the secondary primordium was formed much earlier and metamorphosis was more rapid in faster growing larvae. In summary, the pattern of elarge yellow croaker can be back-calculated based on sagitta size, morphology, and microstructure for measuring early and documentinglarge yellow croaker in the field.