Morphological development of embryos and larvae of Mystus macropterus

Mystus macropterus is a high-quality aquaculture variety that urgently needs to be developed. Exploring the characteristics and patterns of early developmental stages of cultured M. macropterus can provide basic data for its seedling cultivation and large-scale efficient seed production. We studied the morphological characteristics and developmental features of its embryos and juveniles by microscopic observation, and measured the morphological indicators to derive regression equations for the growth characteristics of juveniles. The results show that the fertilized eggs of the fish were oval and yellowish brown, with a diameter of (3.46±0.3) mm. At incubation temperature of 26.2  ℃, the embryos took 79 h to develop for eight stages with 28 periods, including fertilization, cleavage, blastocyst, gastrula, neuroembryo, organ differentiation and hatching, and the total accumulative temperature was 2065.26 h·℃. The total length of the larvae was (7.31±0.52) mm, the larvae stage lasted for 10 d, and most of the yolk sac was absorbed at early stage of larvae. The full-length specific growth rate (SGR_L) was 9.79%, and the weight-specific growth rate (SGR_m) was 12.31%. Most of the larvae opened 7–8 d after membrane emergence, and the yolk sac disappeared on 9^th day. The SGR_L and SGR_m were 4.15% and 12.25% at later stage of larvae, respectively. The juvenile stage lasted for 11 d. The fins were basically mature, and the body size and body color were close to those of adult fish. SGR_L was 4.30%, SGR_m was 13.17%, and the total length was 22–24 mm. The statistical model shows that the growth of the larvae and juveniles is of allometric type.