How do you get goldfish colour back?

To restore a goldfish's color, ensure it receives a balanced diet rich in carotenoids, such as those found in spirulina, krill, and certain vegetables like carrots or sweet potatoes. Maintain optimal water conditions by performing regular water changes and keeping the tank clean, as poor water quality can affect coloration. Additionally, provide appropriate lighting and avoid stressors in the environment to help enhance the fish's natural colors.