Aquaculture industry is one of the fastest growing sectors in animal food production. However, farming of carnivorous fish strongly relies on the use of wild fish-based meals, a practice that is environmentally and economically unsustainable. Insect-based diets constitute a strong candidate for fishmeal substitution, due to their high nutritional value and low environmental footprint. However, information about the potential gut microbiota shifts occurring as a consequence of dietary insect meal (IM) inclusion is still scarce. Thus, this study aims to assess the effect of three different IM, namely, Hermetia illucens larvae meal (HM), Tenebrio molitor larvae meal (TM), and H. illucens exuviae meal (HEM) on European sea bass gut microbiota modulation using high-throughput 16S rRNA gene amplicon sequencing. Sequencing was performed at the Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna under the project ID JMF-2002-2.