Effects of salinity and temperature on embryonic development of the Indian medaka, Oryzias melastigma

The Indian medaka (Oryzias melastigma) being a euryhaline fish, fertilization and embryogenesis occur outside the body of the female. Their development is readily affected by environmental factors such as temperature and salinity. Changes in salinity or temperature may affect the maturation, spawning, fertilization etc. The interaction of various physico-chemical parameters has direct impact on the aquatic life. Knowledge of the pattern of early larval development and the effects of environmental parameters on reproduction is important as it facilitates aquaculture research and fish resource management. In this research, two experiments were conducted to find out optimum salinity and temperature during the embryonic development of Indian medaka. The effect of salinity (fresh water, 5, 10, 15, 20, 25, 30 and 35 g L⁻¹) and temperature (20.0, 22.5, 25.0, 27.5 and 30.0°C) on survival, total hatching rate, hatching period and viability of 24 h. post hatch larvae were investigated separately. Thus, it was noted that 5 g L⁻¹ salinity and 27.5°C temperature were most suitable parameter for better embryonic development of Indian medaka, O. melastigma.