Astaxanthin is one of the most powerful natural ingredients to increase the colorasion of your fish.
Fish can also use it as a vitamin A precursor. It is also important in the reproductive cycles of fish and shrimp, improving fertilization and survival rates during seedstock production of several species.

You can use it at a dose of 0.5-1 % of food.
You can also wet your food pellets and cover them with astaxanthin, then let them dry.