Reproductive Parameters and Sex Cell Ultrastructure in Cinnabar Goatfish Parupeneus heptacanthus (Mullidae) from the Coastal Zone of Nha Trang (Vietnam)

The size composition of the fish, gonadal condition, and oocyte and spermatozoon ultrastructure are studied in Parupeneus heptacanthus from the coastal zone of Nha Trang (southern Central Vietnam). The males are larger than the females, and the body length—body weight relationship is significantly different in the representatives of both sexes. Based on ovarian condition, oogenesis is continuous. Average batch fecundity is 11 056 oocytes. The egg envelope in the end of vitellogenesis (~300 µm in diameter) includes zona radiata 5.0 µm in width and chorion (0.5 µm). Based on spermatozoon head ultrastructure, the species is similar to other species of the genus Parupeneus, but the flagellum is substantially longer reaching on average 63 µm.