The objective of this study was to assess the effect of effective microorganisms (EM) on the growth and survival of Litopenaeus vannamei “white shrimp” reared in a semi-intensive system in the region of Tumbes, Peru. Post-larvae (PLs) of approximately 0.02 g were cultured (15 PLs/m2) in four ponds (E) distributed in two groups: E1-E2 as controls (without EM), and E3-E4 with EM supplementation. EM was added to feed daily and directly to the water weekly. From each pond, 200 shrimps were captured weekly to assess the growth parameter (weight). Analysis of variance and Tukey’s test were used to determine significant differences in weight growth. The water physical- chemical parameters were monitored (daily and weekly), while, organic matter was determined at the beginning and at the end of the experiment. Finally, the economic indicators of the study were evaluated. Significant differ...