From a couple of previous posts I made here in the past.
"Natural astaxanthin sources that have been exploited for aquaculture feeds include the
extracted oils of crayfish and krill, the red yeast
Xanthophyllomyces dendrorhous (formerly
known as
Phaffia rhodozyma) and the freshwater green alga
Haematococcus pluvialis. Because
the crustacean oils and the yeast have relatively low astaxanthin concentrations (0.15-0.40% of
dry weight), they have been commercially less attractive than the algae, which can contain up to
3% astaxanthin by dry weight2.
Haematococcus algae meal has been approved in the United
States, Japan and Canada as a color additive for salmon feeds, and is presently used in the diets
of farmed salmon, trout, sea bream, prawns and ornamental fish."
Through the generous donation of Cyanotech I first began experimenting with the algae based products approx. 25+ years ago. The only things that come close, are the synthetic products, such as Carophyll Red.
Commercial aquaculture facilities don't feed farmed salmon etc, krill, to turn their bland grey flesh, to the color pink. Pink salmon flesh sells, grey not so much.
Same with trout, etc.
Now check out the pics of the Discus I posted below, sans krill, almost 100% single pellet brand diet. (+ bloodworms as a treat 1-2 times a week)
How many Discus? | MonsterFishKeepers.com
Nothing wrong with adding krill to a fishes diet, but color wise, it will not make any type of noticeable difference if one is already feeding a quality diet, and the genetics are there. Sexual maturity will make a huge difference in overall coloration, so don't let that fool you into thinking a coincidental change of diet was the cause.
Beautiful fish, Rich.