'Probably not white, though the colour will become much paler'.
Goldfish and many other animals change colour in response to light levels.If your goldfish is kept in the dark at night, you may notice it appears a little paler when you turn on the lights in the morning. Goldfish kept indoors without full-spectrum lighting are also less-brightly coloured than fish exposed to natural sunlight or artificial lighting that includes ultraviolet light (UVA and UVB).
