Natural colors ?

I just saw the photo of this beautiful angel fish .
I have a question for specialists .
Is naturel red color ?
Hormones or coloring foods ?
In your opinion ?

Red/orange colouration in angelfish is due to the retention of carotenoids. Angels do not produce carotenoids naturally, they obtain them from their diet. All proprietary fish foods contain some carotene. Colour enhancing foods have higher levels of carotenoids, either chemically manufactured, or from natural sources such as algae e.g. spirolina, brine shrimp, cyclops etc.

Red colours in koi angels, such as the one in your photo, are therefore a combination of fish with the right genetics to retain carotenoids and a diet sufficiently rich in carotenoids.
whilst that's a nice example of a koi with a lot of red colouration, breeders in the USA are producing fish with far higher levels of pigmentation. Angels plus produce some of the best, http://www.angelsplus.com/FishKoiSelect.htm but they are quite open about the need to feed a diet rich in carotene to maintain these intense colours.

Finally a good answer to my question .
Thank you very much .

Do you think this food is good to intensify the colors of these angelfish ?

I like tetra foods & generally I feed tetramin flakes to my fish. Pro colour certainly has extra carotene so will help to maintain the colour. Some people add paprika to their fishes diet as a way of really boosting colour, or use foods like cyclop-eeze. The question you have to ask yourself is how comfortable you feel feeding a diet specifically to boost the colour of the fish?
Flamingos are pink specifically because of their natural diet, when kept in captivity it's necessary to add carotene to their diet to stop them turning white, I think most people would consider that a reasonable thing to do, but when it comes to fish different people will have different thresholds as to where the line between, a good diet that helps maintain colour & a diet that artificially enhances/distorts colour, lies.