In this project, the composition of the microbiota of rainbow trout is studied, fed with 2 diets with different levels of protein and carbohydrates (MC/MP and HC/LP), in addition, it was supplemented with a strain of Leuconostoc as a potential probiotic. The experiment lasted 8 weeks. A microbiota characterization of the instetinal content was done using high-throughput sequencing of the V4 region of the 16sRNA gene.