Abstract: 【Objective】The purpose of the study was to analyze the morphological changes and microstructural characteristics of otolith in Siniperca knerii larval and juvenile fish in the lower reaches of the Liujiang River,and to explore the current growth and reproduction status of S. knerii in this section of the river,so as to provide theoretical basis for resource protection and rational development and utilization of S. knerii.【Method】The S. knerii larval and juvenile fish collected from the lower reaches of Liujiang River in 2022 were used as experimental materials. After anesthesia with 50% ethanol,the body length(mm) was measured,and the otolith was selected with anatomical needle. Temperature marking method was used to confirm the increment period of sagitta otolith marking ring. The morphological characteristics of sagitta otolith and lapillus otolith were observed by microscope and the number of otolith marking rings were counted. The incubation date was extrapolated using otolith daily increment technology. The morphological indices of length(μm), width(μm),circumference(μm) and area(μm²) of sagitta otolith and lapillus otolith were measured by Image J. And the shape indices such as circularity,rectangularity,ellipticity,aspect ratio,shape size and roundness were calculated. The morphological changes of sagitta otolith of S. knerii body length of two types of size classes(body length ≤ 13 mm and body length >13 mm) were compared,the relationship between the morphological indices of S. knerii sagitta otoliths and body length was fitted,and the optimal model was selected using Akaike information criterion(AIC)to analyze the relationship between the two.【Result】S. knerii samples collected in 2022 ranged from 3 to 9 lapillus otolith marking rings and 6 to 16 sagitta otolith marking rings. The number of sagitta otolith marking rings was linearly correlated with the marking time. The increment of S. knerii sagitta otolith marking rings was daily periodic,and the day age was represented by the number of daily rings N+3. It was estimated that the incubation period of S. knerii samples in the lower reaches of Liujiang River in 2022 was from May 1 to August 8. With the growth of S. knerii larval and juvenile fish,sagitta otoliths developed from near round to peach-shaped with a slightly pointed end,and lapillus otoliths developed from near round to mussel shaped. Changes of sagitta otoliths were more obvious compared to that of lapillus otoliths. The linear model was the best fitting model to fit the relationship between body length and four morphological indices:length,width,circumference and area of the sagitta otoliths of S. knerii. The correlation between the morphological indices of otoliths and body length of S. knerii in two size classes was strong. The R² of the second class was larger than that of the first class,and there was no significant difference in the linear model fit effects between the two size classes. The results indicated that the otolith morphology of S. knerii larval and juvenile fish was linearly correlated with body length in the early life stage,and the correlation gradually increased in a period of time.【Conclusion】The incubation period of S. knerii larval and juvenile fish in the lower reaches of the Liujiang River is overall shorter than the natural breeding period of Siniperca fishes in the Pearl River Basin. Sagitta otolith is a more suitable organ for early age identification of S. knerii,and the size of the otolith can be used as an important basis for judging the early growth status of this species.