The gut microbiota is an assortment of microorganisms including bacteria, archaea, viruses, and fungi found in animals’ gut with a broad effect on health (Neuman et al 2016).
Gut fish microbiota harbours a varied group of microorganisms that actively contribute to nutrition metabolism and absorption; immunity and stress resistance, and gut function and maintenance (Niu et al 2020, Piazzon et al 2019, Wang et al 2017, Silva et al 2011). This living ecosystem is not exclusively affected by intrinsic factors as sex, age, genetics or microbiome development, but also by external agents like diet, environment, trophic level, season, habitat or developmental stage (Yao et al 2020, Piazzon et al 2019, Egerton et al 2018, Wang et al 2017, Estruch et al 2015).
Feed has shown a robust impact on digestive microbiota reshaping in fish species (Wang et al 2017, Estruch et al 2015, Silva et al 2011). Actually, the core microbiome of carnivorous, omnivorous, and herbivorous fish species is really different (Liu et al., 2016) and a change on diet can modulate their microbiota. For instance, it has been found a shift on a gastrointestinal microbial profile with the inclusion of meat and bone meal in gilthead sea bream diets (Moutinho et al 2017).
Owing to the rapid development of Aquaculture and the gaining interest for FM replacement, knowledge of microbiome function will be relevant to ensure the health statute and suitable nutrition of the future fish (Egerton et al 2018, Piazzon et al 2019).