Effects of different salinity levels on spawning performance, embryonic development and early viability of a euryhaline medaka species, Oryzias dancena, were examined. O. dancena were able to spawn eggs in a wide range of salinity from 0 to 70$^{circ}/_{circcirc}$, however, the spawning frequency was lowered in complete freshwater (0$^{circ}/_{circcirc}$) and in highly salted water (70$^{circ}/_{circcirc}$). Fertilization success was negatively affected when the environmental salinity was higher than the salt concentration found in normal seawater. Embryonic viability and hatching success were also inversely related with the salinity levels. Typical abnormality was observed in developing embryos incubated at high salinities (30, 45 and 60$^{circ}/_{circcirc}$). In addition, the time to hatch was significantly delayed with increasing salinities: peak hatching occurred at 12~14 days post fertilization (dpf) in freshwater and at least at 17 to 18 dpf in 60$^{circ}/_{circcirc}$. Mean survival rates of the hatched larvae up to 7 days post hatching (dph) were at least 97% in salinity levels ranging from 0 to 30$^{circ}/_{circcirc}$. However, larvae reared in 45 and 60$^{circ}/_{circcirc}$ experienced significant mortality, especially in the early phase, resulting in only 75% and 64% survival rates up to 7 dph, respectively.