Prebiotics as functional ingredients: focus on Mediterranean fish aquaculture

The increased demand for food fish, together with the banning of antibiotics for fish growth promotion and the greater public awareness for healthy fish production, led to an increased interest in the potential of functional feeds as health promoters. Prebiotics are functional ingredients that are used in fish, being reported to be associated with improvements in growth, feed efficiency, gut microbiota, digestive enzyme activities, gut morphology, immune status, disease resistance, intermediary metabolism, and stress responses. Those benefits may be related with the increase in gut beneficial bacteria, bacteria end-products of prebiotic fermentation, or the interaction between prebiotics and pattern recognition receptors. Due to the reported prebiotic-related positive effects in fish, a large amount of studies have been published in the last years, mainly focusing on prebiotics' benefits to fish. Thus, the present review focuses on prebiotics' potential as functional ingredients, focusing on their mechanisms of action. In addition, this review summarizes prebiotic effects in Mediterranean aquaculture fish, whose production has greatly increased in the last years. Finally, topics that deserve to be further explored, such as prebiotic effects related with fish age and size, and timing and duration of administration are suggested.