Limited availability of fishmeal (FM) and increasing disease pressure are two key challenges in the sustainable growth of shrimp farming. To successfully reduce FM, an appropriate balance of amino acids (AA) and all essential nutrients are required. Methionine (Met) is typically the first limiting AA which is commonly met with the use of supplemental Met sources. A dipeptide of DL-Met (DL-Methionyl-DL-Methionine) or in short ‘Met-Met’, was shown to be the most effective Met source for shrimps due to its very low water solubility/ leaching and better utilization. As an alternative to antibiotics, an in-feed probiotic based on Bacillus amyloliquefaciens CECT 5940 (Ecobiol®) have shown to improve the health and performance of shrimps. However, the combination of these strategies has not been fully explored. A trial was conducted to determine the effects of Met-Met and Ecobiol® on growth performance of whiteleg shrimp (Litopenaeus vannamei) fed reduced FM diets. A total of 480 shrimps (initial BW = 0.30 ± 0.04 g) were randomly distributed to 24 tanks (150 L each) and fed 6 dietary treatments (4 replicates) for 54 days. Treatments in pellet form were fed 3 times per day including: D1) positive control diet (PC) with 20% FM and no supplemental Met, D2) reduced FM diet with 10% FM (RFM) & 0.13% DL-Met, D3) RFM with 0.06% Met-Met, D4) RFM with 0.19% Met-Met, D5) RFM & 0.13% DL-Met + 0.1% Ecobiol®, and D6) RFM with 0.06% Met-Met + 0.1% Ecobiol®. Diets were isoenergetic and to the same level of essential AA as in the PC (total Lys = 2.11%). Met-Met was used with a Met bioefficacy (BE) of 200% and all diets had the same Met:Lys and Met+Cys:Lys ratios achieved in D1 (33 and 54% respectively) except for D4 that had a greater Met:Lys and Met+Cys:Lys ratios (45 and 66% respectively). Data were analyzed by ANOVA and pre-planned contrast statements. Reduction of FM from 20 to 10% with an adequate balance of Met and other nutrients did not affect (P > 0.05) any of the growth performance parameters (D1 vs. D2 and D3). Replacing DL-Met with 50% Met-Met (D2 and D5 vs. D3 and D6), improved final BW and biomass gain (P < 0.05) and tended (P = 0.06) to reduce FCR suggesting that the BE of Met-Met could be greater than 200%. Increasing the Met+Cys:Lys from 44 to 66% (D3 vs. D4) resulted in numerical greater final BW and reduced FCR. Ecobiol® supplementation (D5 and D6 vs. D2 and D3) improved (P < 0.05) final BW and biomass gain regardless of the Met source used. These results demonstrate that FM levels can be reduced while maintaining an appropriate balance of AA and other nutrients. Increased Met+Cys:Lys resulted on improved performance and survivability. Met-Met is a superior Met source compared to DL-Met with a BE of at least 200% while Ecobiol® supplementation improved final BW and biomass gain. Both strategies (Met-Met and Ecobiol® supplementations) added to a reduced FM diet resulted on improved growth performance compared to a diet with high FM level in shrimps.