The microorganisms use as probiotic, can be a viable alternative to prevent stress, pathogenic agents, and also improvement on growth zootechnical performance indexes. This work aimed to evaluate the pre-selected intestinal bacteria of Nile tilapia from commercial fish-farms in Brazil, utilization on feeding and it is effect as a possible probiotic, evaluating zootechnical growth performance. The experiment was conducted at Fishery Institute – Brazil, for a total of 81 days. The experimental design was entirely randomized, with seven treatments and three repetitions: T0 – control; T1 – Bacillus velenzis (1011); T2 – Bacillus pumilus (3x109), T3 – Bacillus subtilis (1,5 x1012), T4 – Enterococcus hirae (3x1012), T5 – Enterococcus faecium (7x1012) e T6 – mixture treatment. Probiotic were added in 2% soy oil and sprayed in the feed at a dosage of 1g/kg. The result observed was that treatments T2 and T6 promoted an increase in final fish biomass, when compared to control group (p<0,05). We conclude that isolated and pre-selected bacteria from Nile tilapia intestine of group T2 (B. pumilus) and T6 (mix – B. velezensis, B. pumilus, B. subtilis, E. hirae e E. faecium), improve growth performance, and can be used as a probiotic for tilapia.