Farmed salmon are fed pigment supplements because, without them, their flesh would be a dull gray. Wild salmon get their pink and red color naturally from eating shrimp, krill, and other crustaceans. Farmed salmon don’t eat crustaceans, so producers add the same pigment compound to their feed to replicate that familiar color.
Why Wild Salmon Is Naturally Pink
The color in salmon flesh comes from carotenoids, the same family of pigments that make carrots orange and tomatoes red. The specific carotenoid responsible is astaxanthin. Wild salmon spend their lives eating crustaceans loaded with astaxanthin, and the pigment accumulates in their muscle tissue over time. The more they eat, the deeper the color. This is why different species of wild salmon range from pale pink to deep red, depending on their diet and life stage.
What Farmed Salmon Look Like Without It
Farmed Atlantic salmon eat pellets made from fishmeal, fish oil, plant proteins, and vitamins. None of these ingredients naturally contain enough astaxanthin to color the flesh. Without supplementation, a farmed salmon fillet looks grayish-white. One food writer described it as the color of a filing cabinet.
That’s a problem for the industry, because consumers strongly associate pink and red flesh with quality. Research from Oregon State University found that people perceive redder salmon as fresher, better-tasting, and higher quality, even though color has no actual impact on any of those characteristics. Shoppers also expect to pay less for pale salmon and will pay a premium for deeply colored fillets. In studies using a numbered color scale, consumers rated salmon in the 22-24 range (lighter pink) as less valuable and salmon in the 33-34 range (rich red-orange) as worth the most.
So producers add astaxanthin or a related pigment called canthaxanthin to salmon feed. The fish digest it, and the pigment deposits into their muscle tissue, just as it would if they were eating shrimp in the ocean. The process isn’t a surface dye or injection. It works through the same biological pathway that colors wild salmon.
How the Pigment Gets Into the Fish
Astaxanthin is fat-soluble, meaning it dissolves in the oils the fish digest and then gets transported through the bloodstream into muscle fibers. The amount that accumulates depends partly on the dose in the feed and partly on the size of the fish. Larger salmon deposit pigment more efficiently, so color tends to deepen as the fish grows. Producers can adjust the concentration in feed pellets to target a specific shade, effectively choosing how pink the final fillet will be.
Synthetic vs. Natural Astaxanthin
About 95% of the astaxanthin used globally is chemically synthesized. It’s cheaper to produce and more stable in feed pellets, partly because manufacturers coat it in a protective shell (microencapsulation) with added antioxidants to prevent it from breaking down during storage.
Natural astaxanthin comes from microalgae, red yeast, or certain bacteria. It differs from the synthetic version at the molecular level. Natural astaxanthin exists mainly in an esterified form, meaning it’s bonded to fatty acids and needs to be broken down during digestion before the fish can absorb it. Synthetic astaxanthin is already in its free form and is more immediately available. Studies in salmon and trout have found that synthetic astaxanthin is retained in feed better after preparation and storage, and it may deposit into muscle tissue more efficiently. The cell walls of algae and yeast can also reduce digestibility, further lowering absorption of the natural version.
Some premium farmed salmon brands market their use of natural astaxanthin as a selling point, though both forms produce the same visual result in the fillet.
Labeling Rules in the U.S.
The FDA classifies astaxanthin and canthaxanthin as color additives when used in salmon feed. Retailers selling farmed salmon are required to note that the color is added. You’ll typically see a small label on the packaging or at the fish counter that reads “color added” or “artificially colored.” The specific wording and visibility vary, and it’s easy to miss if you’re not looking for it. The FDA regulates which color additives can be used in foods, the maximum amounts allowed, and how they must be declared on labels.
Is the Added Color Harmful?
Astaxanthin is a potent antioxidant, and eating salmon is one of the primary ways people consume it. Research published in Current Developments in Nutrition confirmed that eating salmon fillets measurably raises astaxanthin levels in human blood plasma. The compound has documented anti-inflammatory and metabolic benefits. Wild salmon generally contain higher concentrations of astaxanthin and other health-promoting compounds than farmed salmon, and those levels hold up even after cooking.
The pigment itself isn’t a health concern at the levels used in aquaculture. Canthaxanthin, the other pigment sometimes used, has stricter limits because very high doses (far above what you’d get from eating salmon) have been linked to eye issues in humans. At the concentrations approved for salmon feed, neither compound poses a known risk.
Why Producers Keep Doing It
It comes down to consumer expectations. People have a mental image of what salmon looks like, and gray fillets don’t match it. The Oregon State research made it clear: shoppers use color as a shorthand for freshness and flavor, and they’re willing to pay more for it. Removing the pigment from feed would make farmed salmon significantly harder to sell, even if the taste and nutritional profile stayed the same. For an industry that produces the majority of the world’s Atlantic salmon, that’s not a trade-off producers are willing to make.