Dietary Algae Effects on Fish Health and Performance

Dietary inclusion of macroalgae and microalgae in aquafeeds has emerged as a sustainable strategy to enhance fish growth, resilience and nutritional quality. Algal biomass supplies proteins, essential minerals, vitamins and long-chain polyunsaturated fatty acids while also delivering functional metabolites such as polysaccharides, polyphenols and pigments. These bioactive compounds can modulate antioxidant defences, bolster innate and adaptive immune responses and shape the gut microbiota in ways that improve nutrient absorption and disease resistance. At inclusion levels tailored to species and life stage, algae can partially replace fishmeal and fish oil, reducing reliance on marine resources without compromising growth performance. Moreover, algal feeds confer benefits under environmental stressors—such as hypoxia, temperature fluctuations and pathogen challenge—through enhanced antioxidant enzyme activities and regulated expression of stress-responsive genes. Collectively, research to date underlines the global significance of algae as a multifunctional feed ingredient with wide applications in sustainable aquaculture.

Research from Nature Portfolio

Protective effects of dietary supplementation with a red seaweed extract were demonstrated in European seabass challenged with a bacterial pathogen. Fish fed diets containing 5 % aqueous extract of Gracilaria sp. showed delayed mortality, elevated lysozyme activity and reduced lipid peroxidation compared with controls. Transcript profiles in liver and head-kidney revealed down-regulation of stress-responsive heat-shock proteins and modulation of antioxidant- and inflammation-related genes, indicating that seaweed-derived compounds can fine-tune the host antioxidative and immune machinery to enhance resistance against infection.

Dietary Algae Effects on Fish Health and Performance publication trend

The graph below shows the total number of articles in dietary algae effects on fish health and performance across all publications each year (not limited to Nature Index journals).

Technical terms

Polysaccharides: Large carbohydrate molecules in algae that modulate immunity and gut health.

Polyunsaturated fatty acids (PUFAs): Essential fatty acids found in algae that support growth and stress resilience.

Antioxidant enzymes: Cellular proteins (such as catalase and superoxide dismutase) that neutralise reactive oxygen species.

Gut microbiota: Community of intestinal microorganisms that influence nutrient absorption and immune function.

Feed conversion ratio (FCR): Measure of feed efficiency calculated as feed intake divided by weight gain.

References

1. Seaweed and Seaweed-Based Functional Metabolites as Potential Modulators of Growth, Immune and Antioxidant Responses, and Gut Microbiota in Fish. Antioxidants (2023).
2. Proximate Composition and Fatty Acid Profile of Gilthead Seabream (Sparus aurata) Fed with Pelvetia canaliculata-Supplemented Diets: An Insight towards the Valorization of Seaweed Biomass. Foods (2023).
3. Protective effects of seaweed supplemented diet on antioxidant and immune responses in European seabass (Dicentrarchus labrax) subjected to bacterial infection. Scientific Reports (2019).
4. The Effects of Laurencia caspica Algae Extract on Hemato‐Immunological Parameters, Antioxidant Defense, and Resistance against Streptococcus agalactiae in Nile tilapia (Oreochromis niloticus). Aquaculture Nutrition (2023).