Algae as an ingredient in fish feed
Algae as an ingredient in fish feed is a long-discussed topic in the aquaculture sector. Considered as being too expensive as a raw material in the past, the application of different algae products in fish feed has been limited so far.
With prices of “traditional” raw materials, including fish meal and fish oil, skyrocketing in the recent past, algae might become more attractive in the future.
Another perspective is the quest for more sustainable raw materials to substitute fish meal and fish oil in fish feed, although there is a strong debate within the industry about this topic as well as what “sustainable” means in this respect.
From a biological perspective, both groups of algae, microalgae and macroalgae, offer features that have shown beneficial results when included in fish feed trials.
In the case of microalgae it can be the content of essential amino acids, omega-3 fatty acids like EPA and DHA and vitamins whereas for both microalgae and macroalgae positive effects from bioactive compounds, minerals and antioxidants are discussed in the scientific literature.
Nevertheless, there is an inconsistent picture of the application of algae in fish feeds, despite those positive features above, which is often linked to a lower palatability and digestibility of algae in fish, leading to poorer growth and feed conversion ratio in some studies which in turn is largely dependent on the algae species of choice, its processing, application and degree of inclusion.
The economical feasibility of the inclusion of algae in fish feed is rarely discussed, indicating that algae in fish feed have to deliver specific or strategic benefits for the fish consumer, fish producer and fish feed producer to be economically feasible along the value chain.
Indeed, the application of purified algae oil rich in omega-3 fatty acids EPA and DHA in fish feed created market demand and willingness to pay by the end consumer.
In terms of sustainability, the (partial) replacement of fish meal and fish oil is widely considered a quest of the aquaculture industry to receive a more sustainable image in the public.
On the other hand, other sustainability measures such as the Global Warming Potential given as Carbon dioxide-equivalents have gained interest within the industry to become more transparent in its footprint in times of Global Warming.
Due to its energy-intensive cultivation, harvesting and processing under intensive culture conditions, some initial studies suggest that algae might in fact have a far higher Global Warming Potential than traditional raw materials in fish feed, questioning the sustainable application in the light of Global Warming Potential.
Therefore, different aspects should be taken into account when the sustainability of emerging raw materials is discussed.
In conclusion, algae can be a valuable raw material in fish feeds, targeting specific applications in the value chains.
The consumed volume will increase by improving the nutritional value, investigation of low-cost processing methods as well as specific beneficial modes of actions of algae in fish.