Impact of krill products on the growth, health, and fillet quality of farmed non-salmonid fish

Abstract

The rising global demand for fish as a protein source has led to increased efforts to find sustainable alternatives to reduce the dependency on traditional aquafeed ingredients like fishmeal (FM) and fish oil (FO). However, these conventional ingredients face declining availability due to environmental and economic challenges. While common alternatives to these ingredients, such as plant proteins and oils, reduce pressure on marine ecosystems and provide nutrients, these alternatives have limitations, including the presence of anti-nutritional factors, lack of essential long-chain polyunsaturated omega-3 fatty acids like eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), essential amino acids and reduced palatability. Therefore, high plant-based diets can present issues in terms of fish performance, health and nutritional quality of aqua products for consumers. Furthermore, plant-based ingredients, though cost-effective, possess sustainability challenges and do not support a more circular economy within the aquafeed sector. Novel eco-friendly ingredients, including insect meals, single-cell proteins, and fish co-products are being explored; however, these still face regulatory, scalability, consumer acceptance, and cost issues. Antarctic krill (Euphausia superba), presents a promising sustainable low trophic alternative, as it represents the largest single species biomass. Krill products, particularly krill meal (KM), krill oil (KO) and krill hydrolysate (KH), offer high-quality proteins, astaxanthin and phospholipid-bound omega-3 fatty acids (EPA and DHA), which are more bioavailable than traditional marine lipid sources. Further, commercially available krill products are supported by extensive scientific evidence demonstrating their benefits in various fish species when included in feeds. This review evaluates the benefits of krill products on the performance, health, fillet quality and reproductive performance of non-salmonid farmed fish, focusing on studies from the 1980s to the present. Several studies reported positive effects of krill products in enhancing growth performance, feed conversion, and nutrient metabolism, as well as boosting stress resistance, survival, and health status. Krillsupplemented diets have also shown improvements in reproductive performance and fillet quality, though research in these areas remains limited in non-salmonids. In addition, the regulatory framework governing Antarctic krill harvesting ensures minimal environmental impact, sustainable sourcing, and traceability, aligning with industry standards and consumer demands for eco-friendly products. Collectively, all these outcomes support the inclusion of krill products in aquafeed formulations to non-salmonid fish species to enhance the growth, health, fillet quality, and reproductive performance while addressing sustainability challenges. However, the higher cost of krill products compared to the traditional feed ingredients may challenge the broader adoption of krill diets. Therefore, to assess the cost-efficiency and optimal supplementation of aquafeeds with krill products, future studies are warranted to include comprehensive economic analyses, detailed cost-benefit evaluations, and comparisons of the cost-effectiveness of krill products against other novel and traditional aquafeed ingredients.