In a 30-day experiment, Farfantepenaeus brasiliensis PL25 (25 ± 10 mg; 17.9 ± 1.6 mm) were raised in nine circular floating cages with a stocking density of 1000 shrimp m−3. Three treatments were evaluated: (1) culture in BFT system plus a commercial feed supply (BFT+CF); (2) culture in BFT system without feed supply (BFT) and (3) culture in clear water with feed supply (control). Post-larvae (PL) final weight (218.9, 236.5 and 176.0 mg, for BFT+CF, BFT and control respectively), final biomass (17.9, 15.7 and 8.2 g) and weight gain (193.9, 211.5 and 151.0 mg) were similar in the BFT regardless of whether they were fed a commercial diet (P>0.05), but were both significantly higher than the control (P<0.05). Survival (81.5%, 67.0% and 84.8% respectively) and final length did not differ between treatments (P>0.05). The biofloc analysis identified five main microorganism groups: protozoa (ciliate and flagellate), rotifers, cyanobacteria (filamentous and unicellular) and pennate diatoms. Free living bacteria and attached bacteria in bulk were 25.73 ± 8.63 and 0.86 ± 3.17 × 106 mL−1 respectively. Proximate analysis in the biofloc indicated high levels of crude protein (30.4%). Results confirmed favourable nutritional quality of biofloc, and enhanced growth and production of F. brasiliensis PL in biofloc systems.