Koi Colour Enhancing

The colors on the koi is caused by pigment colors are hidden under the skin of fish.Pigment color will develop if there are foods that support its development. Fish in the wild will obtain natural red, orange and yellow color pigments, via carotenoids, through natural food sources such as shrimps, snails, daphnia and blood worms. Pond's lack these natural food sources so the fish require a supplement to their diets. Unfortunately natural color enhancers are an expensive addition to a diet, so many fish foods do not contain them or they are provided in such small quantities they are not effective.



Carotenoids are a family of over 600 natural lipid-soluble pigments that are produced within microalgae, phytoplankton, and higher plants. They also produce compounds such as essential fatty acids, steroids, sterols, vitamins A, D, E, and K. Within the various classes of natural pigments, the carotenoids are the most widespread and structurally diverse pigmenting agents. They are responsible, in combination with proteins, for many of the brilliant yellow to red colors in plants and the wide range of blue, green, purple, brown and reddish colors of fish and crustaceans.

Carotenoids are absorbed in animal diets - sometimes transformed into other carotenoids, and incorporated into various tissues. As we all know, flamingo's are pink or should be pink - this is due to ingesting algae containing high levels of beta-carotene and then converting this yellow carotenoid into canthaxanthin and astaxanthin before depositing it into the feathers and tissues as red plumage.

Some fish species such as koi and various crustaceans have the enzymatic mechanisms to convert carotenoids into other forms as well, such as astaxanthin - some fish/animals don't. Astaxanthin is the optimal carotenoid for the proper pigmentation of the red/pink colors is aquaria.

Crustaceans and other aquatic animals are unable to produce astaxanthin de novo (naturally), only plants and protists (bacteria, algae, fungi) are capable of synthesizing carotenoids. Therefore astaxanthin must be available in either their native habitat or manufactured diet to meet nutritional requirements. In the natural aquatic environment, astaxanthin is biosynthesized in the food chain within microalgae or phytoplankton at the primary production level. The microalgae are consumed by zooplankton, insects or crustaceans which accumulate astaxanthin, and in turn are ingested by fish which then accrue astaxanthin.


Source:
http://www.canadiankoiandpond.ca/articles/article16.html