Abstract: The bluespot mullet (Moolgarda seheli) is an economically important species in China’s coastal waters. To investigate the otolith microstructure characteristics and explore their relationships with key developmental events during early growth stages, we analyzed larval and juvenile M. seheli specimens collected from the surf zones of Gaolong Bay, Wenchang City, Hainan Island, from June to October 2021, along with their sagittal otoliths. Results showed that the hatching dates of the collected individuals ranged from April 16 to September 19, 2021, with a peak occurring between June and August. The larval growth rate (b) was 0.2003±0.0362, ranging from 0.1404 to 0.3332. The first secondary primordium (SP) formed at (20.3±3.8) days post-hatching (range: 12—30 days), corresponding to a standard length of (16.92±1.79) mm, ranging from 13.07 to 21.41 mm. Individual sagittal otoliths contained (2.9±1.6) SPs, ranging from 0 to 7. Our findings revealed that larvae with higher growth rates initiated SP formation earlier and developed more SPs. The initial formation of SP appears to coincide with a significant developmental event, potentially marking the transition from the larval to juvenile stage. As a widely distributed and commercially important species in nearshore habitats, these results enhance our understanding of the growth and developmental dynamics of larval and juvenile M. seheli, providing valuable insights for future research on their reproductive biology, nursery habitats, and population recruitment processes.