Can Astaxanthin Powder Be Used For Fish?

Can Astaxanthin Powder Be Used For Fish?

Yes. Astaxanthin is a ketocarotenoid primarily used in fish farming as a colorant, antioxidant, and immune enhancer. The effectiveness of astaxanthin powder as a feed additive depends on the source of the raw material (natural extraction or chemical synthesis), formulation stability, dosage, and the physiological stage of the fish.

What is Astaxanthin?

Astaxanthin has the molecular formula C₄₀H₅₂O₄ and a molecular weight of 596.85. It is a dark red powder. Its molecular structure contains conjugated double bonds and terminal ketone and hydroxyl groups, resulting in high lipophilicity. Natural astaxanthin powder is insoluble in water, slightly soluble in vegetable oils, and readily soluble in organic solvents such as dichloromethane and acetone. Astaxanthin is sensitive to light, heat, oxygen, and low pH environments, and is prone to cis-trans isomerization and oxidative degradation during feed processing and storage. Therefore, commercial astaxanthin bulk powder typically employs microencapsulation, esterification, or the addition of antioxidants (such as ethoxyquinoline and vitamin E) to improve stability.

Can Astaxanthin Powder Be Used For Fish?

After fish ingest astaxanthin-containing feed, the substance undergoes the following processes in the digestive tract:

• Emulsification and Release:

Astaxanthin in the feed must coexist with dietary fat, forming chylomicrons under the action of bile salts.

• Absorption:

Absorbed via the brush border of small intestinal epithelial cells, free astaxanthin enters cells through passive diffusion or SR-BI receptor-mediated transport.

• Transport:

After re-esterification within intestinal cells, it binds to chylomicrons and enters the bloodstream via the lymphatic system.

• Deposition:

Natural Astaxanthin powder is mainly deposited in the skin, muscle, ovaries, and liver of fish. In salmonids, koi, and goldfish, astaxanthin binds to actin or specific apolipoproteins, exhibiting a red to orange-red phenotype.

The utilization efficiency of pure astaxanthin powder varies among different fish species. Salmonids (such as Atlantic salmon and rainbow trout) can convert some zeaxanthin and canthaxanthin into astaxanthin through enzymes in intestinal mucosal cells, but the conversion rate is lower than that of directly fed astaxanthin. Most other carnivorous or omnivorous fish (such as red sea bream and yellow catfish) lack the ability to convert astaxanthin and must rely on direct addition to their feed.

Astaxanthin Powder in Major Farmed Fish

• Salmon

Salmon flesh color is a key indicator for market pricing. Wild salmon obtain astaxanthin by consuming crustaceans, while farmed salmon must supplement it through feed. Research data shows that Atlantic salmon require an astaxanthin addition of 40–80 mg/kg of feed (on dry matter) for 8–12 weeks to achieve a muscle astaxanthin concentration of 5–8 mg/kg, with flesh color matching grades 27–30 on the SalmoFan™ color chart. There is no statistically significant difference in deposition efficiency between synthetic and natural sources (from Haematococcus pluvialis), but the bioavailability of naturally esterified astaxanthin is slightly lower than that of free astaxanthin.

• Ornamental Fish (Koi, Goldfish, Blood Parrots)

Ornamental fish have higher requirements for body color than edible fish. The recommended addition of astaxanthin powder to koi feed is 100–150 mg/kg. Continuous feeding for 4–6 weeks can enhance the brightness and saturation of red patches. Goldfish and blood parrots respond significantly to astaxanthin; adding 50–100 mg/kg can expand and deepen the red areas on their bodies. It should be noted that astaxanthin cannot change the skin color of fish that do not originally possess red genes; it only enhances the expression of existing red pigment cells.

• Marine Economic Fish (Red Sea Bream, Grouper, Large Yellow Croaker)

In red sea bream farming, adding 30–60 mg/kg of astaxanthin bulk powder can make their abdomen and fins pink to bright red, meeting market consumer preferences. For grouper, astaxanthin is mainly deposited on the abdominal skin and the lateral line area of the caudal peduncle; the coloring effect reaches a stable plateau when adding 60 mg/kg. Large yellow croaker has a lower deposition efficiency of astaxanthin and usually needs to be used in combination with canthaxanthin or capsanthin to achieve the desired golden yellow appearance.

Antioxidant and Anti-stress Effects of Astaxanthin

Astaxanthin's ability to scavenge free radicals is 100 times that of vitamin E and 10 times that of β-carotene (based on the singlet oxygen quenching rate constant). In fish farming, this characteristic manifests as:

• Relief of oxidative stress:

Under high-density farming conditions, adding 50–100 mg/kg astaxanthin powder to feed can reduce serum malondialdehyde (MDA) levels by 20–35% and increase the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px).

• Resistance to high-temperature stress:

During the high-temperature period of summer, adding 80 mg/kg natural astaxanthin powder to rainbow trout feed reduced mortality by approximately 40% compared to the control group, and shortened the feed intake recovery period by 3–5 days.

• Resistance to hypoxic stress:

In water bodies with dissolved oxygen below 3 mg/L, tilapia pre-fed with astaxanthin (60 mg/kg, for 14 days) showed a survival time extended by 1.8–2.5 hours.

Effects on Fish Growth Performance and Feed Efficiency

Astaxanthin itself does not directly provide energy or essential amino acids, but it indirectly promotes growth by improving antioxidant status. Meta-analyses (covering 28 studies involving 5 fish species) showed that:

• When astaxanthin was added at 40–80 mg/kg,

its specific growth rate (SGR) increased by an average of 5–12%, and its weight gain (WG%) increased by 8–18%.

• Feed conversion ratio (FCR) decreased by 0.05–0.15:

This is mainly attributed to astaxanthin's role in maintaining intestinal microvillus height and reducing inflammation levels.

Juvenile fish (body length <5 cm) responded more strongly to the growth-promoting effects of astaxanthin than adults; the recommended addition level is 60–100 mg/kg.

Is Astaxanthin Powder Safe For Fish?

China: According to the Ministry of Agriculture and Rural Affairs' "Catalogue of Feed Additives," astaxanthin (natural or synthetic) can be used as a colorant in fish feed, with a maximum limit of 100 mg/kg (as astaxanthin) for salmonids and 80 mg/kg for other fish.

• EU:

EU Regulation 358/2014 stipulates that the maximum addition level of synthetic astaxanthin in salmon and trout feed is 100 mg/kg of complete feed. There is no upper limit for natural astaxanthin (derived from Haematococcus pluvialis), but the source must be labeled.

• USA:

The FDA classifies astaxanthin as GRAS (Generally Recognized as Safe), allowing its addition to salmonid feed up to 80 mg/kg.

• Quality requirements:

Purity (HPLC method) ≥5% or 10% is a common specification; heavy metals (as Pb) ≤10 mg/kg; arsenic ≤2 mg/kg; dioxins ≤1.5 pg WHO-TEQ/g. Synthetic astaxanthin requires additional control over the cis isomer ratio (all-trans ≥ 95%).

Conclusion:

In summary, astaxanthin powder is a proven functional feed additive with clear scientific evidence regarding its effects on fish coloration, antioxidant defense, and growth promotion. Fish feed formulators should select appropriate formulations based on the target fish species, farming stage, market size, and feed processing technology. The recommended starting dose is 50 mg/kg for salmonids, 80 mg/kg for ornamental fish, and 40 mg/kg for marine commercial fish, with adjustments made based on coloration feedback. Feed companies should reduce processing losses through premixing, low-temperature granulation, or post-coating technologies, while also extending shelf life through antioxidant systems.

In the global market, china astaxanthin powder is widely produced and exported by astaxanthin powder manufacturers, including china natural astaxanthin powder manufacturers, natural astaxanthin powder manufacturers, and professional astaxanthin powder suppliers. Leading astaxanthin powder factory and pure astaxanthin powder factory systems focus on producing pure astaxanthin powder and natural astaxanthin powder, offering bulk natural astaxanthin powder and astaxanthin powder bulk supply. Market demand and astaxanthin powder price vary depending on purity, specification, and application, and many suppliers maintain natural astaxanthin powder in stock for fast delivery.

Guanjie Biotech provides astaxanthin powder products that comply with Chinese, EU, and US regulations, with specifications covering 5%, 10%, and customized contents. The products utilize microencapsulation technology, and their high-temperature resistance meets the requirements of extruded feed processing. The company implements ISO 22000 and HACCP quality control systems, providing HPLC purity test reports and heavy metal and solvent residue test data for each batch. Our products have been exported to over 100 countries and regions and are suitable for use as a feed additive for farmed fish such as salmon, koi, and red sea bream. For business inquiries and sample requests, please contact: info@gybiotech.com.

References

[1] European Food Safety Authority (EFSA). (2014). Scientific opinion on the safety and efficacy of synthetic astaxanthin as a feed additive for salmon and trout, other fish, ornamental fish, crustaceans and ornamental birds. EFSA Journal, 12(6), 3724.

[2] European Food Safety Authority (EFSA). (2014). Scientific opinion on the safety and efficacy of astaxanthin (CAROPHYLL® Pink 10% CWS) for salmonids and ornamental fish. EFSA Journal, 12(6), 3725. https://doi.org/10.2903/j.efsa.2014.3725

[3] European Commission Joint Research Centre. (2025). Astaxanthin (2a161j): Renewal of authorisation for use in fish, crustaceans and ornamental fish feed. European Commission Technical Report.

[4] European Commission Joint Research Centre. (2010). Astaxanthin (2a161j): Recommended analytical methods for feed additives and feedingstuffs. Technical Report.

[5] Ambati, R. R., Phang, S. M., Ravi, S., & Aswathanarayana, R. G. (2014). Astaxanthin: Sources, extraction, stability, biological activities and its commercial applications—A review. Marine Drugs, 12(1), 128–152.

[6] Storebakken, T., Foss, P., & Schiedt, K. (1987). Austreng E. Carotenoid deposition in rainbow trout from astaxanthin supplemented diets. Aquaculture, 65(3–4), 279–292.

[7] Torrissen, O. J. (1989). Pigmentation of salmonids: interactions of astaxanthin and canthaxanthin on pigment deposition in rainbow trout. Aquaculture, 79(1–4), 363–374.