While your goldfish may not turn completely white without any light whatsoever, they may become much paler. Goldfish do change colour as a response to light levels as they have chromatophores which produce the pigments that give colouration, or reflect light.
They do get some of their colouration from the types of food they eat as some of the food may contain pigments called carotenoids, or the food has had a pigment called canthaxanthin added to it.
So some folks say. I prefer to keep my fish happy and give them as near to natural conditions as possible.
It Blows Up
The short answer to this question is 'probably not white, though the color will become much paler'.
goldfish do
the lack of light being in the dark
Yes!
If a goldfish is kept in the dark it will appear lighter in the morning, So if left in the dark for a long period of time, a goldfish will turn almost white. If kept in the light, it will absorb color, and often become a brighter gold. (almost the same as when we tan, the sun gives us color, and when we get less of it we turn whiter, or lighter)
It will eventually turn white.
Goldfish usually react positively to having a light source, however it is unhealthy to leave your fish tank illuminated constantly and the light also encourages algae to grow rapidly. Eight to twelve hours a day is sufficient for a happy goldfish.
Very dark, all the time, but truthfully it isn't healthy for the goldfish to be subjected to such conditions and it is just plain cruel to force a goldfish to stay in a dark room all the time.
Goldfish are not particularly attracted to any one colour.
It will turn white, or at least will start having some loss of color.
It has been reported that goldfish will loose colour if kept in low light conditions so I guess if you are silly enough to want to not see your fish and keep them (it) in the dark to find out if it goes white that is your right.
When ever you don't feed him or her.