Is farmed salmon ‘artificially coloured’? The facts about astaxanthin and food dyes.
Last month, the U.S. Food and Drug Administration banned Red Dye No. 3—a colouring found in everything from pastries to pills—citing studies linking it to thyroid cancer in animals. The dye had already been prohibited in cosmetics since 1990, yet it remained in food and medicine for decades.
Activists have sought to draw an equivalence between this and the use of astaxanthin in farmed salmon, arguing that both are synthetic pigments added to alter appearance. The comparison is misleading. While Red Dye No. 3 is purely cosmetic, astaxanthin is a naturally occurring dietary component essential to salmon health.
Wild salmon develop their pink-orange hue by consuming crustaceans rich in astaxanthin, while farmed salmon, which do not have access to the same diet, receive the compound through their feed. Without it, their flesh would not be “grey,” as some claim, but rather a pale off-white or light pink, similar to other fish species that do not consume carotenoid-rich diets.
Unlike synthetic food dyes, astaxanthin is not merely a pigment—it is an antioxidant with biological benefits. Chemically related to beta-carotene, the compound that gives carrots their color, astaxanthin is widely sold as a dietary supplement for its potential anti-inflammatory and eye health benefits. It plays a crucial role in salmon growth, immune function, and overall well-being.
Regulators, including the European Food Safety Authority (EFSA), the U.S. Food and Drug Administration (FDA), and the World Health Organization (WHO), have approved the use of astaxanthin in aquaculture. While some premium salmon producers opt for algae-derived astaxanthin to appeal to consumer preferences for “natural” ingredients, the synthetic version is structurally identical and serves the same function.
The claim that farmed salmon are “artificially colored” reflects a broader skepticism about modern food production. In reality, wild and farmed salmon derive their color from the same pigment, whether through a natural diet or a formulated feed. The result is the same—and no, farmed salmon are not being dyed like candy.
So what about the infamous SalmoFan?
The SalmoFan (see illustration above), often cited in discussions about the color of farmed salmon, is a color-matching tool used by the aquaculture industry to ensure consistency in fillet pigmentation. It is sometimes portrayed as evidence that farmed salmon are being artificially “dyed,” reinforcing the misconception that their color is unnatural. In reality, the SalmoFan serves a quality control function, much like standardized color charts used in other food industries, from cheese to egg yolks.
The tool was developed by DSM, a major supplier of astaxanthin, and consists of a series of swatches ranging from pale pink to deep red. Salmon farmers and processors use it to match fillet color to consumer expectations, just as coffee producers assess roast levels or winemakers compare hues in red wine.
Its existence has been seized upon by critics who argue that it exposes an industrial process of “coloring” salmon flesh to appeal to consumers. However, the reality is more mundane: just as wild salmon display a range of colors depending on their diet and species, farmed salmon’s pigmentation can vary depending on feed composition and astaxanthin levels. The SalmoFan simply provides a reference to maintain consistency across different batches of fish, avoiding variations that might be perceived as lower quality by consumers.
Framing the SalmoFan as evidence of “artificial coloring” misrepresents how farmed salmon pigmentation works. The fish are not dyed; they are absorbing a dietary pigment in the same way wild salmon do. The industry’s use of a standardized color guide does not make farmed salmon any more artificial than a dairy aiming for the right shade of yellow for its butter.
