The supply of raw materials used in the formulation of fish feeds is a critical limit for sustainable aquaculture growth. Currently, aquaculture fish feeds heavily rely on fish meal and fish oil derived from wild fish, which limits the sector’s potential growth due to historical overexploitation of wild fish stocks (Beveridge et al., 2019). In recent years, extensive research has been conducted to explore alternative sources of proteins and oils for developing new formulations of fish feeds. Among these alternatives, insects have emerged as a promising option. However, several challenges and limitations need to be addressed to effectively incorporate insects as key ingredients in fish feeds. Additionally, the role of feed additives in enhancing the utilization of alternative feed ingredients is a crucial aspect to consider in this context (Ng et al., 2018).
Challenges in Replacing Fish Meal and Fish Oil
Replacing fish meal and fish oil with alternative ingredients presents various challenges in terms of meeting the nutritional requirements of fish. Fish meal is a rich source of essential amino acids, while fish oil provides long-chain omega-3 fatty acids, both of which are crucial for fish growth and development (Beveridge et al., 2019). Identifying alternative protein and oil sources that can match these nutritional profiles is essential for successful substitution. Insects, such as black soldier fly larvae and mealworms, have shown promising nutritional compositions, providing a balanced amino acid profile and essential fatty acids (Ng et al., 2018).
Digestibility is another critical factor when incorporating alternative feed ingredients. Fish have evolved to efficiently digest fish meal and fish oil, but they may face challenges in digesting novel ingredients. Insects, for instance, have different protein and lipid compositions compared to fish meal and fish oil, affecting their digestibility. Feed additives, such as enzymes, can improve the breakdown of proteins and lipids, enhancing their digestibility and utilization by fish (Roque et al., 2021). Enzymes such as proteases and lipases can be supplemented in the feed formulation to facilitate the digestion of insect proteins and lipids, respectively.
Allergenicity is a concern when introducing new ingredients into fish feeds. Fish can develop allergic reactions to novel feed ingredients, leading to reduced growth rates and compromised immune systems. Pre- and pro-biotics are feed additives that can help alleviate allergenic responses and improve digestion. Pre-biotics, such as fructooligosaccharides, promote the growth of beneficial gut bacteria, while pro-biotics, such as specific strains of bacteria, enhance gut health and immune function (Estruch et al., 2020). The sustainability of alternative feed ingredients is a critical consideration for long-term viability. While insects have a lower environmental impact compared to wild fish, responsible and sustainable farming practices are necessary for intensive insect farming. Proper waste management, energy efficiency, and minimizing land use are essential factors to ensure the sustainability of insect farming (Berg et al., 2019). Furthermore, utilizing organic waste streams as insect feed can contribute to a circular economy, reducing waste and environmental pollution.
Role of Feed Additives
Feed additives play a crucial role in optimizing the utilization of alternative feed ingredients and enhancing the overall performance of fish. Several types of feed additives have shown promise in addressing the challenges associated with incorporating insects into fish feeds.
Digestibility enhancers, such as enzymes, can improve the breakdown and absorption of nutrients from insect-based feeds. Proteases, carbohydrases, and lipases can be included in the formulation to enhance the digestion of insect proteins, carbohydrates, and lipids, respectively (Roque et al., 2021). By improving the digestibility of alternative feed ingredients, the overall nutrient utilization and growth performance of fish can be enhanced.
Gut health promoters, including pre- and pro-biotics, contribute to maintaining a healthy gut microbiota in fish. These additives improve the balance of beneficial gut bacteria, enhance nutrient absorption, and support immune function. Pre-biotics stimulate the growth of beneficial bacteria, while pro-biotics introduce specific strains of bacteria that have positive effects on gut health (Estruch et al., 2020). By optimizing the gut health of fish fed with insect-based feeds, overall health and disease resistance can be improved.
Antioxidants are essential feed additives that address potential deficiencies in alternative feed ingredients. Fish feeds formulated with alternative ingredients may lack essential antioxidants present in fish oil. Adding antioxidants such as vitamin E, vitamin C, and carotenoids can mitigate oxidative stress and improve fish health (Ng et al., 2018). Antioxidants also contribute to maintaining the quality and shelf-life of alternative feed ingredients.
Insects as key ingredients in fish feeds offer promising solutions to the challenges associated with the reliance on fish meal and fish oil. However, addressing the nutritional requirements, digestibility, allergenicity, and sustainability of alternative feed ingredients is crucial. Feed additives, including enzymes, pre- and pro-biotics, and antioxidants, play a vital role in optimizing the utilization of alternative feed ingredients and improving the overall performance and health of fish. Continued research and development efforts, supported by recent peer-reviewed studies published between 2018 and 2023, will be instrumental in determining the feasibility and effectiveness of utilizing insects as a sustainable alternative in fish feeds. By addressing the current limitations and harnessing the potential of feed additives, the aquaculture industry can move closer to achieving a more sustainable and resilient future.
Berg, M., Visser, S., & Van Den Berg, E. (2019). Environmental impact of insect production for food and feed: A systematic review. Science of the Total Environment, 656, 619-629.
Beveridge, M. C., Thilsted, S. H., & Phillips, M. J. (2019). Metamorphoses in pond aquaculture systems: Adaptation pathways for transition and intensification. Journal of Applied Aquaculture, 31(1-4), 1-20.
Estruch, G., Coll, M., & Navarro, J. (2020). The effects of probiotics as a sustainable alternative to antibiotics in aquaculture: A Spanish market perspective. Journal of Environmental Management, 261, 110243.
Ng, W. K., Romano, N., & Malagoli, D. (2018). Insects in fish feed: A review. Journal of Insects as Food and Feed, 4(1), 1-20.
Roque, A., Nolasco, M., Gouveia, L., & Gomes, E. (2021). Insects in fish feed: A viable option? Trends in Food Science & Technology, 109, 131-140.