Goldfish tend to change color over their lifespans, which may indicate an issue or be just part of their aging process. This is particularly common among fancy breeds bred for specific color patterns which tend to fade as they mature and age.
As is commonly known, animal colors are determined by pigment cells called chromatophores in their skin. These cells produce various hues to reflect or absorb light; when the chromatophores don't receive sufficient UV lighting they produce paler colors similar to how sunburn affects human skin cells. Therefore, providing ample UV lighting for goldfish ensures their chromatophores receive sufficient stimulation.
Oxygen shortage is another potential cause of color loss in goldfish, though it may take longer for it to manifest itself until your fish starts acting strange. To combat this problem, perform regular water changes and ensure the tank's parameters remain at their ideal levels.
Goldfish fisheries should maintain an optimal environment to help preserve their beautiful coloration. Incorporating foods like Spirulina algae and Bentonite clay into their tank diet will assist your goldfish in maintaining its vibrancy.
