<p>This study investigated the effects of biofloc on the growth parameters, water footprint, and digestive enzyme activity of <i>Arapaima gigas</i> juveniles. Two treatments were used: biofloc technology (BFT) and clear water exchange (CWE) by 50% day⁻¹. The fish were stocked at a density of 30 fish m⁻³ and fed experimental feed for 45&#xa0;days. No significant differences were observed in the yield, survival, final weight, or feed conversion ratio among treatments. However, significant differences were observed in water quality, where the total ammonia nitrogen, N-NO₂, and N-NO₃ were higher and the water footprint was lower in the BFT treatment compared to that of CWE. Total proteolytic activity, trypsin, and lipase of fish cultured in BFT increased at the end of the experiment; however, chymotrypsin and amylase remained unchanged over time. In CWE, total protease increased over time, trypsin and lipase decreased, and chymotrypsin and amylase remained unchanged. After 25&#xa0;days of culture, total protease, trypsin, and chymotrypsin were significantly equal among treatments. Lipase activity was higher in BFT, while amylase activity was higher in CWE. At the end of the experiment, the total protease and lipase were higher in fish in the BFT, trypsin and chymotrypsin were significantly equal, and amylase was higher in fish in CWE. These results demonstrate that it is possible to reared <i>A. gigas</i> in a biofloc system, without significant differences in growth performance, in addition to the decrease in the apparent water footprint and the presence of enzymatic activity.</p>