In this study, we compared the development of tambaqui Colossoma macropomum in excavated tanks with and without mechanical aeration. The experiment was conducted in a semi-intensive system, which used two 600 m2 nurseries (tanks) populated with 500 juveniles, from September, 2014 to August, 2015. They were submitted to weekly biometry of 50 individuals and the follow-up on water quality control. At the end of the farming period, the final weight (1.96 ± 0.44 kg with aeration and 1.95 ± 0.24 kg without aeration) and the other performance indicators were statistically similar (p > 0.464). It is therefore concluded that the use of aerators is unnecessary for tambaqui farming in a semi-intensive system.