This book uniquely combines basic biology and aquaculture to define gaps in the nutritional research and practices of farmed fishes and invertebrates. Due to the positive effects of prebiotics on human health and aging, adding prebiotics to aquafeeds, either individually or in various combinations, is becoming more widely adopted. This is one of the fastest-growing areas of aquatic animal nutrition. Although the underlying mechanisms are relatively well documented, they are not fully understood. The main objective of developing and using prebiotics as functional feeds is to enhance growth, reproduction, immunity, and resistance to pathogens and stress. This goal is often achieved with low-dose supplementation, but not with excess doses. However, the excess range and long-term application are rarely well documented and require further research.
Prebiotic supplementation includes β-glucans, chitin, and other saccharides in complex and oligomeric forms. Sulfated saccharides from marine macroalgae are of growing interest. Other prebiotic supplements include hemicelluloses and various soil components, such as clay minerals, black carbon (biochar), and humic substances. Discussions of prebiotics emphasize epigenetic mechanisms such as trained immunity and DNA methylation as an epigenetic clock. Trained immunity appears to be more widespread than anticipated. While it is beginning to be understood, it deserves intensive study. Research on the epigenetic clock in aquatic animals is in its infancy, but, inspired by human research, it is expected to provide indications of age, health, and nutritional status for aquatic counterparts.
