We are frequently asked about what we feed our koi to put color on them. It's a complex answer and involves far more than just food, but the food is an important item.
First, the mechanism by which koi become orange is not what most think. Angelfish do not produce any pigment in the color range of yellow-orange-red. They derive these pigments from their foods. Foods that have carotenoids in them are what they need to get any of this color range. Fortunately, most foods have some of these pigments in them, including live foods, frozen foods and manufactured fish foods. So, you ask, "How does genetics play a role in this if it's the food". This is a bit more simple. The fish have the genes that direct the storage of these pigments in a skin layer. Through selective breeding we increase the potential for more color, both in intensity and coverage.
You might think, that's simple enough so why doesn't everyone have really orange koi? This part is the most complex and least understood. Basically, it comes down to stress. The carotenoids are used in the immune system to fight stress, so instead of storing them, the fish uses them. Stress is bad and it can come from a thousand things - some not very obvious. This means that you have to not only feed correctly and have fish with great genetics, but you must avoid any kind of stress if you want the best of color on your koi.
Today, we're concentrating on the food. We love using our Color Primal Pellet to add color to our fish. They grow well on it, readily eat it, and the color definitely is better with it in their diet. The below video shows the feeding response we get from a tank of young koi eating the 0.5mm size.
This tank has fish from two spawns in it. the smaller ones are too young to show good color yet. The larger ones are about 3.5 months old and show much of their potential at this stage. As they age, the color will get deeper, but it will probably not spread to body areas that do not already show color. These are not our best colored koi. This video is just to show the feeding response.
Hopefully, this gets you started to raising more colorful koi. Good luck!