The marble goby, Oxyeleotris marmoratus (Eletoridae) is the largest freshwater gobioid fish in the world and is the most expensive freshwater fish in Southeast Asian countries. Rapid development for the culturing techniques of this fish has increased the demand of the juvenile. However, the stable seed rearing technique has not yet been established due to high mortality occurred during the early juvenile stage or after 40 days after hatch (d AH). To develop a seed rearing technique, an experiment on different salinity levels (SaLs) was conducted to determine the optimum SaL on growth and survival at the early juvenile stage (40 to 100 d AH). The optimum SaL was 10 ppt throughout the whole period in this experiment. The mean body weight (BW) and survival rate at 100 d AH in 10 ppt SaL were 0.31 g and 85.6% respectively, those being significantly higher (P<0.05) than those in the other SaLs. The most important period of the salinity adjustment was in 40 to 70 d AH for the juvenile rearing of O. marmoratus. After 70 d AH it is possible to rear the fish either in freshwater or brackishwater.