This study evaluated the effects of amino acid supplementation on lambari (Astyanax bimaculatus) cultured in a biofloc technology (BFT) system and in clear water (RAS) using a factorial design. Over 45 days, fish were fed diets containing 34% crude protein (CP), supplemented with lysine and methionine (3% biomass). No significant differences were observed in growth parameters, final weight, total weight gain, or feed conversion ratio (FCR) among diet groups and culture systems. However, significant differences in biomass, FCR, and survival were detected between the culture systems. Fish reared in the BFT system showed superior performance for these parameters (p < 0.05). Average biomass was 50.79 g in BFT and 39.80 g in RAS, while survival was higher in BFT (97.5%) compared to RAS (84.1%). Proximate composition analysis revealed that fish reared in BFT had higher crude protein and ash contents, but lower crude fat and dry matter levels (p < 0.05). Under the experimental conditions, it can be concluded that amino acid supplementation is unnecessary and that the biofloc system is an efficient strategy for lambari culture.