For assessing the feasibility of otolith alizarin complexone (ALC) marking of crucian carp Carassius auratus and providing a useful reference to develop batch marking technologies for the release and enhancement of this species or even other cyprinidae fish, juvenile C. auratus (Fig. 1) were used to investigate the deposition of ALC onto otolith by immersing it in 100 mg/L for 5 d and the dynamic changes of ALC markings among three types of otoliths at different days of subsequent culture after the immersion. The results showed that ALC marking rings were detected on the sagittal, lapillus and asteriscus under visible light, green and blue excitation light with a marking rate of 100% without extra impact on survival and growth of the fish (Fig. 2). However, the marking effect of different otoliths was different. Under fluorescence, asteriscus showed the best marking effect, followed by lapillus, while under visible light, lapillus had the best marking effect, followed by asteriscus (Fig. 3). With the extension of the days of the subsequent culture, the visible light marker gradually weakened and almost disappeared at 20 d. However, under the green and blue excitation light, the fluorescence intensity of the ALC marking ring kept almost stable and was maintained for a long time (Table 1). Moreover, the marker ring could be easily observed under blue excitation light (Fig. 4). In combination with data of mortality, total length and body weight, it is believed that immersion by 100 mg/L ALC for 5 d can achieve satisfactory effect for otolith marking of juvenile C. auratus.