Aeration is commonly used to improve water quality in ponds and enhance production of farmed aquatic animals. Dissolved oxygen is a major factor in intensive production and it is directly related to aeration rate (Hopkins et al., 1991). McGraw et al. (2001), working with L. vannamei and Litopenaeus stylirostris, showed that increasing minimum dissolved oxygen by aeration resulted in higher survival, yield, and net income, although no significant differences occurred in final weight. We found a positive effect of higher dissolved oxygen on final weight and that dissolved oxygen, in turn, was controlled by the starting time of aeration.