This study investigates the survival and development of Metapenaeus ensis larvae and postlarvae fed the diatom Chaetoceros gracilis and Artemia nauplii. Survival rate from protozoea I to 6- or 7-day-old postlarvae ranged from 35 to 63% (mean = 45%) in shrimp from four spawns fed C. gracilis alone. Supplement of Artemia nauplii beginning at the protozoea III stage did not improve the survival and developmental rates of myses and postlarvae. The mean body length of 9-day-old postlarvae from a single spawn reached about 3 mm regardless of the addition of Artemia nauplii. It was concluded that C. gracilis is an adequate diet for rearing M. ensis throughout the hatchery operation of its aquacultural practice.