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Why is my salmon really red?

Why is my salmon really red?

Salmon is one of the most popular fish consumed around the world. Its bright orange-red color is one of its most distinctive attributes. But why exactly does salmon have such a vibrant hue? The red color of salmon flesh comes from astaxanthin, a naturally occurring pigment that salmon obtain from their diet. Understanding the source of salmon’s red color provides insights into salmon biology, nutrition, farming practices, and even cooking methods.

What Causes the Red Color in Salmon?

The reddish-orange color of salmon flesh comes from pigments called carotenoids. Carotenoids are natural fat-soluble pigments produced by plants and some other organisms like algae. Animals that eat carotenoid-containing plants or organisms can accumulate carotenoids in their tissues.

The main carotenoid responsible for salmon’s red color is called astaxanthin. Wild salmon get astaxanthin by consuming shrimp and krill that dine on astaxanthin-containing microalgae. Farmed salmon are fed astaxanthin supplements made from algae meal or oil. Without astaxanthin in their diet, salmon flesh would be pale and unappetizing.

Astaxanthin’s Origins and Health Benefits

Astaxanthin is a type of carotenoid called a xanthophyll. It has potent antioxidant properties and is considered a superior antioxidant compared to other carotenoids like beta-carotene. Astaxanthin helps protect cells from oxidative damage and inflammation.

This pigment is produced by a type of green microalgae called Haematococcus pluvialis. When the algae encounter stressful conditions like excessive sunlight or low nutrition, they ramp up astaxanthin production. The astaxanthin helps shield the algal cells from damage.

Salmon gain this protective antioxidant by consuming astaxanthin-rich krill and shrimp. In turn, astaxanthin is passed on to humans when we eat salmon. Research suggests astaxanthin may benefit heart health, vision, skin aging, exercise recovery, and cognition in people.

Differences in Astaxanthin Levels

Not all salmon have the same depth of red hue. Wild salmon typically display the deepest, brightest red-orange flesh. The astaxanthin content of wild salmon ranges from 4-15 mg per kg. Sockeye salmon tend to be the reddest and highest in astaxanthin.

Farmed salmon have access to less astaxanthin from natural sources and are fed supplemental astaxanthin. They contain around 5-20 mg astaxanthin per kg but usually appear paler than wild salmon.

Within a salmon population, larger, older fish tend to be redder and higher in astaxanthin. Spawning salmon also develop a deeper reddish color from heightened astaxanthin deposition in preparation for the reproductive journey upstream. The chart below compares astaxanthin levels across different salmon types and environments:

Salmon Type Astaxanthin Content
Wild Sockeye 6-15 mg/kg
Wild Coho 4-11 mg/kg
Wild King 4-8 mg/kg
Farmed Atlantic 5-13 mg/kg

Benefits of Astaxanthin for Salmon

Salmon gain several benefits from accumulating astaxanthin:

  • Powerful antioxidant protection – Defends cells against oxidative damage
  • UV light screening – Protects skin and eyes from sun damage
  • Immune function – Enhances immune response and resistance to disease
  • Reproductive development – Important for sexual maturation
  • Cardio-respiratory capacity – Improves muscle endurance for migration

Research also suggests that astaxanthin supplementation makes farmed salmon hardier and more resistant to sea lice infestations.

Cooking Impact on Astaxanthin

Astaxanthin levels can be impacted by cooking and preparation methods. Raw salmon has the highest astaxanthin content. One study found that baking salmon fillets caused a 30% loss of astaxanthin, while pan-frying fillets led to a 60% reduction.

Poaching, steaming, and sous vide cooking resulted in intermediate astaxanthin losses around 45%. Slow, moist cooking methods help minimize astaxanthin degradation compared to high-heat cooking.

Canning salmon has the largest impact, with up to 80% of astaxanthin destroyed in the canning process. However, one advantage of canned salmon is the bones are left intact, providing substantial calcium benefits.


The vibrant red-orange hue of salmon flesh comes from astaxanthin, a carotenoid pigment salmon accumulate from their diet. Wild salmon obtain more astaxanthin from eating astaxanthin-rich krill and algae, giving them a deeper red color. Farmed salmon are fed supplemental astaxanthin but still tend to be paler.

Astaxanthin provides salmon with antioxidant protection, enhances reproduction and immunity, and boosts endurance for migration. In people, astaxanthin may improve heart health, vision, skin, exercise recovery and cognition.

Salmon preparation impacts astaxanthin levels, with raw salmon containing the highest amounts. Slow, moist cooking methods help preserve more astaxanthin compared to frying or baking. Canned salmon has significantly lower astaxanthin due to processing, but provides beneficial calcium from bones.

Overall, the red color of salmon provides a visual clue into its exceptional nutrition and health benefits. So next time you enjoy a beautiful salmon fillet, you can appreciate just how important astaxanthin pigmentation is for salmon biology and human nutrition alike.