Color enhancement, explained

Have you ever wondered whether those fish foods claiming to enhance the color of your fish will actually work? The simple, short answer is “often.”

astaxanthin molecule

Chemical structure of astaxanthin, a carotenoid commonly used to enhance fish coloration. Photo courtesy of Wikimedia Commons.

Fish coloration is determined by three factors:

  • Genetics—whether the fish has inherited the necessary genetic material to show certain colors
  • Nervous system and glandular factors— coloration depends on a fish’s mood and general health. All things being equal, a sick fish is probably less colorful than a healthy one. Males also may develop develop strong colors to attract females, and how the color of subordinate males lessens in the presence of dominant males
  • Dietary factors—nutrients and chemical compounds that the fish eats, which directly or indirectly influence color.

After providing optimal conditions, the aquarist’s next opportunity to influence fish color is by introducing coloring agents into the fish’s diet.  (See also “How to make fish food,” on this blog.

I won’t spend any time on the practice of injecting fish with dyes or paints  to change their colors. It’s cruel to the fish, and I hope you won’t buy any fish whose color has been altered through such artificial means.

The substances that influence fish color and coloration the most are carotenoids.  Carotenoids are compounds produced by plants, algae, and certain fungi.  Generally, they’re produced to help collect light, most often for photosynthesis, the chemical process by which plants generate their own food.

For the most part, animals (like fish) don’t produce carotenoids, and have to get them from eating plants, or eating animals that ate plants. Cichlid Forum has a nice page explaining the role of these substances in bringing out the colors of fish. In general, carotenoids accumulate in the tissues of animals. For example, Flamingo feathers aren’t naturally pink, but get that way from accumulating carotenoids in the crustaceans and algae that the flamingoes eat. In zoos, flamingos are given feed with a carotenoid (canthaxanthin) in it to keep up their color.

Astaxanthin powder

Astaxanthin powder is available from many online supplliers

Astaxanthin is the carotenoid that is probably the most well known and most widely added to fish foods. It’s produced by marine algae and bacteria and is passed up the food chain and accumulates in the shells of shrimp, crabs and lobsters. It is also the principal carotenoid responsible for the red flesh of salmon. A series of experiments by researchers at Hawaii’s College of Tropical Agriculture and Human Resources showed that adding the bacteria, Haematococcus pluvialis, which contains astaxanthin and other carotenoids, to fish foodd worked to intensified the colors of red velvet swordtails, topaz cichlids, forktail rainbowfish, and, to a lesser degree, 24K mollies and kissing gouramis.

Package of dried shrimp.

Dried shrimp, a good source of astaxanthin, is available in many Asian grocery stores.

Carotenoids range from red, to orange to yellow. Most commercial color formulas contain astaxanthin, a red carotenoid that can bring out red color. In my experience, it’s harder to find color formulas to bring out orange or yellow. The way I provide my fish with carotenoids of orange and yellow is to make my own fish food that contains sources of orange and yellow carotenoids. Here’s a rundown of the additives and foods I’ve had success with in bringing out the color in my fish.

In my fishroom, I’ve found that food containing astaxanthin really brings out the reds in white cloud mountain minnows, Fundulopanchax scheeli, Gymnogeophagus rhabdotus, and in the fins of clown loaches. You can order chemically synthesized astaxanthin from online suppliers. Another source is ground, dried shrimp or krill.

Discus breeders often add paprika to their home-made discus food recipies. Paprika, is made from a ground, dried pepper, Capsicum annuumPaprika is rich in a number of carotenoids, including beta carotene, capsanthin and capsorubin.

Spoonful of paprika

Paprika is a great source of carotenoids in the orange range

In my fishroom, I’ve used paprika to intensify the color of ruby red aulonocaras, orange sailfin mollies, scraper mouth cichlids, and Neolamprologus leleupi. Ground marigold petals also a good source of orange carotenoids, but I haven’t tried them so I couldn’t tell you for sure. Chicken farmers will sometimes add ground marigold petals to chicken feed to give the skin of dressed birds and orange tint. Likewise, eggs from hens fed marigold petals will have more orange yolks than those not provided with a source of orange carotenoids.

clown loach and ruby red aulonocara

In my experience, astaxanthin brings out the red color in the fins of clown loaches, and paprika enhances the orange in ruby red aulonocaras.

Zeaxanthin and lutein are perhaps the most well known yellow carotenoids. They’re present in the yellow vegetables like corn (maize) and probably in the yellow variety of snap beans and the yellow form of bell peppers. They’re also found in egg yolk, a binder that’s often used in home made fish food recipes.

In my fishroom, I’ve added egg yolks and yellow peppers and sometimes yellow snap beans to my home made food to bring out the yellow color in the yellow variant of yellow labs (Labidochromis caeruleus).

yellow lab and hybrid

I added egg yolk and yellow bell peppers to home made fish food to bring out the color in these yellow labs.

In their study, the University of Hawaii researchers cited previous research which found that fish could sometimes metabolize carotenoids and use them to intensify colors in a different range from the carotenoid the consumed. For example, Discus fed astaxanthin and Beta carotene (orange) intensified the fish’s blue coloration.

Discus fish

Fish may sometimes metabolize carotenoids and use them to intensify colors in a different range from the carotenoid the fish consumed. For example, one study found that discus fed astaxanthin and Beta carotene (orange) intensified the fish’s blue coloration.

The Cichlid forum post on fish coloration stated that the non-carotenoid pigment, phycocyanin, brings out the blue color in fish. Phycocyanin is produced by blue green algae, which are contained in spirulina preparations. I haven’t kept all that many blue fish, so I can’t tell you from my experience whether or not it works.

Aulonocara stuartgranti sp. chilumba

The non carotenoid pigment, phycocyanin, is reputed to bring out blue coloration. Phycocyanin is produced by blue green algae and contained in spirulina preparations. Shown here is an Aulonocara stuartgranti sp. Chilumba

Before I conclude this post, I’d like to say that I don’t think “color enhancement” is the best term. If you add something to fish food to bring out a fish’s natural colors, you’re adding something that the fish probably had access to in nature (or something a lot like it) to restore the fish’s natural color, color lost in captivity. So you’re not enhancing color, you’re restoring it. So “Color restoration” seems like the most accurate description to me.

3 Responses to Color enhancement, explained

  1. Paul says:

    I wonder if turmeric would work as a yellow pigment?

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