Reproductive features of Upeneus margarethae (Mullidae), a species recorded in the coastal zone of Vietnam for the first time

The species Upeneus margarethae described recently from the western Indian Ocean is recorded in the coastal zone of Vietnam for the first time. The reproductive features of the representatives of the species from southern Central Vietnam (Nha Trang Bay), Central Vietnam (Da Nang), and North Vietnam (Ha Long Bay) are studied. Based on the analysis of maturity stages of female’s ovaries and gonadosomatic index, the fishes spawn over the entire year in Central Vietnam, but the spawning interruption is observed in North Vietnam during a winter season. In Nha Trang Bay, 50% of females reach sexual maturity at the body length (FL) 9.8 cm. Based on histological structure of ovaries and frequency distribution of oocyte diameter before the spawning, the oogenesis is continuous. Anomalous oocyte structure is registered in 20% of the females. Egg morphology is described for 3 h after activation of ovulated oocytes. A comparison of reproductive parameters in U. margarethae and U. tragula is conducted.