Red fish, white fish, pink fish - fish flesh comes in different colors, mostly depending on the species. However, even fish of the same species can sometimes have different colors. This often confuses consumers, who aren’t sure what the color difference means.

Our technologist, Levan Tomashvili, explains that besides species, several other factors determine a fish’s color. These include its habitat, diet, and gender. He goes into detail about some interesting aspects of fish color and what it can tell us.

Color and Quality

The color of a fish’s flesh doesn’t indicate its quality. Each species has its characteristic flesh color, although you might encounter lighter or darker shades.

Color and Age

As fish get older, their color changes from white (or silvery) to dark gray or even black on the back. Two fish of the same size may have different colors because they are different ages. For example, one might be six months old and the other one year, but they weigh the same.

Simply put, darker color usually indicates an older fish. As the fish ages, its flesh becomes firmer and fattier, which also makes it tastier. So, generally, the darker and larger the fish, the more flavorful it is.

Color and Gender

In some fish species, like salmon, you can easily distinguish males from females by color. Male salmon are usually darker than females.

Color and Activity Level

Another important factor that affects a fish’s color is its activity level. This is linked to a protein called myoglobin, which supplies oxygen to the muscles. The more active a fish is, the more oxygen and therefore more myoglobin, it needs. Less active fish tend to have darker flesh near their fins and tails, which are their most active body parts. Salmon and tuna, which live in the deep ocean, have naturally red flesh.

Color and Diet

You’ve probably heard the saying that you are what you eat and the same goes for fish. For example, salmon have pink or red flesh because they eat shrimp and krill, which contain a reddish-orange pigment called carotenoid. The more of these foods a salmon eats, the darker its color. Farmed salmon, which don’t have access to shrimp or krill, are fed feed enriched with the carotenoid astaxanthin, which also acts as a powerful antioxidant.

Color and Flesh Temperature

The color of fish flesh can also change depending on how it’s stored. For example, frozen fish, including salmon and tuna can become paler. So if you see a lighter-colored frozen fish at the store, don’t assume it’s low quality.