Filler Feed from Marine Micro- and Macroalgae

Aquaculture is expected to overtake capture fisheries in the near future for the production of consumable proteins in the form of seafood. Even though capture fisheries have plateaued based on their landing mass, a significant proportion of this capture is converted to fishmeal and fish oils for use as aquaculture feed. Since sustainability and maintenance of ecological balance are critical for the fishing industry, various alternative aquaculture feeds are being investigated for the replacement of fishmeal and oil. Microalgae have traditionally been used as aquaculture feed, and a substantial quantity of the global biomass production is procured for this purpose. Even though macroalgal cultivation is part of maritime aquaculture, macroalgal biomass has been specifically applied as feed for certain aquaculture species. Algal biomass contains considerable amounts of non-digestible polysaccharides which could be applied as dietary fiber or filler in aquaculture feeds. Pigments such as astaxanthin and antioxidants present in the biomass protect against pathogenic infection and stress encountered in intense farming practices. This chapter discusses the role of microalgae and macroalgae biomass as filler feed in aquaculture. Biomass constituents of algae that confer potential health benefits are discussed, and various studies representing the use of algal biomass as aquaculture feeds are summarized. Conclusions and future perspectives are presented.