Nine 0.11-ha earthen ponds were stocked on 15 May 1997 with Litopenaeus vannamei and L. stylirostris postlarvae in similar proportions at a total density of 33 animals/m 2. Ponds were equipped with automated temperature and dissolved oxygen (DO) concentration data acquisition devices that sampled ponds every 30 min. Aspirator-pump aerators (0.75 kW) were automatically activated when DO fell to 65% (4.6 mg/l at 29°C and 15 ppt salinity), 40% (2.8 mg/l at 29°C and 15 ppt), or 15% (1.1 mg/l at 29°C and 15 ppt) of saturation. Mean shrimp yield, survival of both species, and profitability increased linearly as minimum DO concentration increased from 15% to 65% of saturation ( P<0.05). Higher yields were positively correlated with higher survivals. Final mean shrimp weights were not significantly affected by minimum DO concentrations ( P>0.05).