Study evaluates effects of dietary astaxanthin on farmed fish growth and feed utilization

Results showed optimal supplementation levels of 300-400 mg/kg for growth, 100-200 mg/kg for survival

The results of research presented in a recent paper by scientists in China emphasize the potential of the carotenoid pigment astaxanthin as a multifunctional feed additive to promote sustainable aquaculture; however, its efficacy depends on species, dosage, and environmental context, thus necessitating further mechanistic and optimization studies.

The study – authored by corresponding author Dr. Shuang Liang together with several researchers from the Tianjin Key Laboratory of Aqua-Ecology and Aquaculture, the Key Laboratory of Smart Breeding (Tianjin Agricultural University) and the Tianjin Fisheries Research Institute (Tianjin, China) – discusses research that evaluated the effects of dietary astaxanthin on the growth and feed utilization of aquacultured animals across diverse studies, species, trophic level, and habitat through a meta-analysis.

“This meta-analysis represents a comprehensive quantitative evaluation of astaxanthin’s effects across diverse aquaculture species. By analyzing 64 studies covering 33 species, the research provides evidence-based guidance showing that dietary astaxanthin significantly improves growth performance (with weight gain increases of up to 89 percent), reduces feed conversion ratios, and enhances both antioxidant capacity and immune function. The study also identifies optimal supplementation levels (e.g., 300–400 mg/kg for growth, 100–200 mg/kg for survival), offering practical guidance for the aquaculture industry to improve production efficiency and animal welfare through this natural feed additive,” Dr. Shuang Liang, corresponding author of the study, told the Advocate.

Meta-analysis, a statistical analysis technique that synthesizes results from a group of independent studies related to a specific topic and design, enables comprehensive understanding of research questions and identification of sources of variability in outcomes. In recent years, this methodology has seen preliminary applications in aquaculture nutrition, analyzing the impacts of aquatic feed composition variations [25,26] and water quality management on aquatic species.

Carotenoids are a class of natural functional pigments used in coloring roles that also play critical functions as antioxidant supplements and multifunctional biological agents in aquaculture. Among these, astaxanthin is known for its superior antioxidant properties, significantly outperforming traditional antioxidants such as beta-carotene and vitamin E. Consequently, it is widely utilized as an additive in manufactured aquafeeds: as a xanthophyll carotenoid, it directly enhances product quality by providing commercially desirable pigmentation to fish skin and fillets, with its pigment deposition function being well-established.

Numerous studies have reported that as a functional additive, astaxanthin improves aquatic organisms’ growth performance, survival rates, reproductive health, and egg quality optimization, and also enhances overall health by boosting endogenous enzymatic and non-enzymatic antioxidant systems, strengthening immune defense mechanisms, and exerting anti-inflammatory effects. Although there have been qualitative analyses (descriptive reviews) summarizing the effects and mechanisms of astaxanthin on the growth and health of farmed fish, no quantitative analyses (or meta-analyses) have been conducted to quantitatively evaluate the application effects of astaxanthin in aquatic animals.

From a thorough literature search, 64 high-quality articles covering 33 farmed species were included in this meta-analysis to evaluate the effects of dietary astaxanthin on the growth and feed utilization of farmed aquatic animals. The results demonstrate that dietary astaxanthin supplementation significantly improves final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER) in aquacultured species.

Findings showed that the average effect sizes of FBW, WGR, SGR, PER, and FCR in the astaxanthin-supplemented group compared with the control group are all beneficial for aquaculture animals. This indicates that, on average, adding astaxanthin to the feed can significantly improve the growth performance and feed utilization rate of aquacultured animals. The growth-promoting effects of astaxanthin supplementation may be attributed to its multifaceted physiological roles, including improvement of intestinal morphology, thereby enhancing the absorption of nutrients.

Demand is growing for natural astaxanthin for aquaculture feeds and this Hawaiian biotech company is poised to take advantage

Results also showed that dietary astaxanthin supplementation significantly improved the survival rate of aquacultured animals. This may be related to the findings from this study that dietary supplementation of astaxanthin significantly improved several hepatopancreas antioxidant biomarkers and immune-related parameters in aquacultured animals. And as a strong antioxidant – oxidative stress is a key determinant of fish health – found in nature, astaxanthin has been proven to have antioxidant activity in many studies.

Also, several studies have demonstrated that astaxanthin can improve the immune function of the body through various mechanisms, including cellular immunity and humoral immunity of the body. Supplementing feed with astaxanthin can enhance the antioxidant defense capacity of the organism, strengthen its resistance to oxidative stress, inhibit the inflammatory and apoptotic (apoptosis is a form of programmed cell death that occurs in multicellular organisms) reactions, and improve the survival rate of aquaculture animals.

“Given the multi-faceted physiological functions of astaxanthin, the current quantitative meta-analysis indicates that adding astaxanthin to the feed significantly improves the FBW, WGR, SGR, SR, and FCR of aquaculture animals. Furthermore, supplementation with astaxanthin has exerted positive effects on the digestive, antioxidant and immune functions of aquaculture animals,” concluded the authors. “Therefore, astaxanthin is a promising feed additive for promoting the growth of aquaculture animals, and it is of great significance for sustainable aquaculture. However, the optimal inclusion amount of astaxanthin and the effect of astaxanthin on the growth performance of aquatic animals are closely related to the developmental stage of the animals, the breeding environment, species differences, the source of astaxanthin, and the duration of feeding. Further research is needed to explore the mechanism of the impact of astaxanthin on the growth of aquatic animals in the future.”

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