Abstract: The early morphological development of the temperate fish Miichthys miiuy were described including the observations on the embryo, larval and juvenile fish stages. The fertilized eggs are transparent and buoyant. At the temperature of 25~27℃ and salinity of 32.9, the fertilized eggs developed into larval fish in 19 h. Based on the morphological development, we have established the definition of different stages as the follows: (1) larval fish stage: 1~17 d postfertilization, development of all fins was completed; (2) juvenile fish stage: 18~32 d postfertilization, occipital bone spine appeared and the whole body was covered by scales; (3) young fish stage: 33 d postfertilization. The optimal growing temperature was 25.8~32.2℃ and the salinity was 32.5. The morphological characteristics of the egg size (0.91 mm), oil balls (0.33 mm) and occipital bone spine were found to be different from other species in Sciaenis.