Complete artificial propagation and characteristics of early growth and development of Epinephelus corallicola

This study aimed to achieve indoor full artificial breeding of E. corallicola and explore the characteristics and growth rules of its embryonic and post-embryonic development under indoor full artificial conditions. In this study, broodstocks were subjected to nutritional enhancement until gonadal maturation, and fertilized eggs were obtained through artificial insemination. Microscopic photography and morphological measurement methods were used to systematically track the hatching process of fertilized eggs, as well as the cultivation processes and morphological characteristics of larvae, juveniles and fry. The fertilization rate of E. corallicola fertilized eggs obtained by artificial insemination in this study was ≥97%, and the hatching rate was ≥95%. These are transparent, separated spherical floating eggs with an egg diameter of (0.845±0.025) mm, containing a single oil globule with a diameter of (0.189±0.012) mm. In seawater with a salinity of 33.5±0.5 and a water temperature of (26.5±0.5)°C, the fertilized eggs completed the embryonic development process in 20 hours and 23 minutes through 8 stages covering 28 developmental periods, and entered the larval stage. Pre-larvae aged 0-3 days had unabsorbed yolk sacs and did not open their mouths; on the 4th day, the yolk sac was absorbed and the mouths opened. From the 7th to 22nd days, the second dorsal fin spine continued to grow, reaching its maximum length from the 20th to 22nd days, marking the end of the larval stage. From the 23rd to 36th days, the second dorsal fin spine continued to shorten, scales appeared, and body color formed, marking the end of the juvenile stage. After the 37th day, they entered the fry stage, with hard scales covering the whole body, obvious lateral lines, and fully developed organs and skin mucus glands. This study is the first to complete artificial insemination, spawning and early seedling cultivation of E. corallicola indoors. It reveals the early development chacharacteristics and rules of its full artificial breeding, fills the research gap in the artificial breeding field of this species, incorporates this species into the artificially controllable germplasm resource protection system, and lays a theoretical and technical foundation for subsequent large-scale cultivation.