Optimization of culture conditions with regard to the combined effects of salinity and temperature on biomass and fatty acid production of four thraustochytrid isolates were undertaken. Two strains of Schizochytrium mangrovei (IAo-1 and IXm-6), and one isolate each of Schizochytrium sp. (BSn-1) and Thraustochytrium sp. (IRa-8), isolated from fallen mangrove leaves, were used in this study. Results of the physiological study show that the best growth condition for Schizochytrium isolates was at a salinity range of 15-30 ‰ at 20-30°C, while that for Thraustochytrium sp. was at 22.5-30 ‰ at 25°C. Highest biomass production was 350 mg 50 mL^-1 for Schizochytrium spp., and 133 mg 50 mL^-1 for Thraustochytrium sp. Total lipid content (% freeze-dried biomass) ranged from 16.0-33.2% for S. mangrovei, 13.0-39.1% for Schizochytrium sp., and 11.4-37.5% for Thraustochytrium sp. Highest lipid production was observed at 15-22.5 ‰ salinity (25°C) for S. mangrovei, and at 15 ‰ (25°C) for Schizochytrium sp. and Thraustochytrium sp. Palmitic acid (16:0) and docosahexaenoic acid (DHA; 22:6n3) were the major components of the total fatty acid (TFA) content, comprising about 39-42% and 24-35%, repectively.