So we've established it's not a hybrid, take that out of the equation. No rotkeils I've had were remotely Asian, none of them ever so much as sniffed a hormone their own bodies didn't produce naturally. So that's my lineage baseline.
As far as nutrition, yes, you can overfeed a fish on certain 'color enhancers' and get unnatural colors, but in themselves carotenoids are natural pigmented nutrients, important to health, and found in the plants, bugs, seeds, crustaceans, shellfish, algaes, other fish, etc. that any fish eats in the wild in the first place. In fact, many who pond raise their fish in the summer to feed naturally on the bugs, algae and whatever else nature provides say they get better color than their tank raised fish. How carotenoids affect coloration in an animal depends on it's natural biology; for example, red/orange carotenoids become blue in some fish due to the way they're bound to proteins, the same as blue crabs get their blue from orange/red carotenoids. Virtually all commercial fish foods have carotenoids in them, the better ones by virtue of their natural ingredients, compared with the preponderance of potato, rice, oat meal, feather meal, and similar ingredients in some cheaper foods. So normal premium foods that thousands of other guys also feed equals my feeding baseline.
Here's what I'm used to seeing in young rotkeils I've had-- roughly 9 year old video I dug up:
For the sake of size comparison, the wild female in the video was 8 inches. Was never a big fish photo guy and only ever did a couple of videos some years ago, largely because I didn't have much of a camera until recently, anyway, so video quality is mediocre. (Excuse the couple of odd peacocks, etc. in the tank, they just were temporary extras in a tank that was mostly for growouts, anyway.)
So, don't know, maybe you just have a little different individual, or if he looks normal to Jeff, maybe it's the parents he happens to have vs. the parents I had, but what's in the video is what I'm used to seeing.
