So, are there red koi angelfish? Let's get this out of the way. No, they don't exist - anywhere! There are some adult koi angelfish that are a reddish orange color, but since the degree of redness is unpredictable, and generally much closer to orange. We prefer not to use the word red in our descriptions, especially since no juvenile koi will have any sign of red. As for our lines, you will be hard pressed to find koi anywhere that have more color coverage or greater intensity of color. Still, all juveniles will appear orange and most adults will be more orange than red looking. If you order from others advertising "red koi angelfish", don't say I didn't warn you. 🙂
Koi Angelfish Color Genetics This is a fish with a very complex color genetic makeup. The only known gene interactions are from Gold Marble and Stripeless alleles. There is great variability in the expression of orange pigment, but total number of genes involved is not known. The requirements to get good expression are also not completely understood. A non-stressing environment is very important and foods containing carotenoids are also necessary in developing and maintaining color. Angelfish cannot produce orange pigment. They can only get it from their food. So, if your foods do not contain carotenoids, your koi will have no orange. Don't worry too much about the foods, since most commonly available fish foods contain a good amount of these carotenoids. We recommend freeze dried plankton, freeze dried brine shrimp, krill meal and a good color flake or pellet.
It appears that orange coverage is controlled primarily by genetics but also greatly influenced by environment. There may be some breeders feeding a color enhancing substance that is not natural in foods, but if they are, we are not aware of what that substance might be. If so, you will find it difficult to replicate their results. We only feed our own products available in our Supply Store - with all natural color enhancing foods.
Cautions: Keep these things in mind when looking at photos of Koi on the internet: Representing the color on Koi angelfish is a very tricky thing. First, camera hardware and software that interprets color, varies greatly. Camera flashes can both wash out color and in some instances, greatly enhance it. Monitors that are not calibrated can show colors in many different shades and photo editing software can manipulate photos to look tremendously different from real-life appearances. Also, the spectrum of the light source on the aquarium will greatly affect the look of the fish. Overall, internet photos can be very deceiving. We do our best to represent our fish the way we see them in our tanks. When preparing photos, we do it on calibrated monitors, but it doesn't mean that your monitor will reproduce it the same way, or that your aquarium lighting will reflect the colors in the same way as ours. Also, just because a person's photos come straight from the camera, doesn't mean they accurately represent that person's fish. Camera software makes colors greatly over-saturated out of the box. Camera manufacturers do this on purpose.
In addition to the above problems, the color can fade under stress. In general, the younger they are, the less intense the color will be, even on very well cared for fish in ideal water. It fades somewhat just catching them in a net. Shipping causes it to fade, aggressive fish chasing them, overfeeding, a tank that frightens them, too many plants that deplete oxygen at night, breeding stress and many other stresses can cause the color to fade. When you received shipped-Koi, the color when received won't be as intense as when they were shipped. Also, some people are just unlucky. They have water, that for whatever reason, simply will not allow the best color to get or remain intense in their Koi. They can receive fish with great intensity, but will themselves never be able to reproduce it in their own fry.
In general, koi angelfish with the right conditions, have their color get more intense as they age. At the same time the percentage of coverage generally goes down a bit as the fish matures. Adults that are 100% orange (except where there is black) are still fairly rare at this time from most breeders. We however are to get a good percentage of these with our stock and husbandry.
Koi are not the easiest fish to work with in regards to color. For those who do everything right and have great water, they can seem simple. For the unlucky and inexperienced, it can seem as if the color is artificial and they're being duped by the seller. If you purchase fish that are already well colored, at least you know the stock has the potential (genetics) under the right conditions.