Artificial Reproduction, Larval Rearing, and Gonadal Development of the F1 Generation in Shrimp Scad (Alepes djedaba)

Alepes djedaba is a coastal fish species of high economic value. However, information on its early developmental biology remains incomplete, which limits its application in large-scale seed production. In this study, fertilized eggs were obtained through hormone-induced spawning. Under controlled conditions, microscopic observation and histological sectioning were used to systematically record and analyze embryonic development, larval growth characteristics, and the gonadal development potential of the artificially bred first-generation (F1) offspring. The results showed that the fertilized eggs of A. djedaba are spherical and pelagic with a single oil globule. The egg diameter is (672.02 ± 10.03) μm, and the oil globule diameter is (189.76 ± 8.82) μm. At a water temperature of 24.50–24.97 °C, embryonic development is divided into 6 periods (20 stages), taking 19 h 28 min to complete hatching with an average hatching rate of 22.9% ± 15.6%. The total length of newly hatched larvae is (1.43 ± 0.09) mm, with an average daily growth of 0.39 mm from 0 to 21 days post-hatching (DPH). Furthermore, the testes of the F1 generation cultured in captivity exhibit complete tissue structures and mature spermatozoa, while the ovaries show orderly development primarily dominated by stage II–III oocytes with some early stage IV oocytes. This confirms at the histocytological level that the artificially bred offspring possess normal gonadal development, providing strong evidence of its reproductive potential. This study clarifies the key stages of early development and the adaptability of A. djedaba in captive environments, providing critical theoretical support and basic data for subsequent large-scale seed production and larval rearing optimization.