The short answer to this question is 'probably not white, though the color will become much paler'.
If you have ill treated a goldfish so badly and kept it in the dark for so long that it has lost its colour and gone white IMO you should not have a goldfish or any other kind of living creature to look after.. Common sense would suggest that given time the fish will return to its normal colouring. You certainly will not change a naturally white goldfish into a different colour.
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.
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.
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)
they can live in goldfish bowls i have always kept my beta in a goldfish bowl and my last beta lived between 4-5 years in a goldfish bowl.
It would die.
If your fish has turned white as opposed to become covered in white fungussy stuff, you can assume that is simply the fish developing its adult colouring. Goldfish start off grey/silver and as they grow up their adult/mature colours develop. If it is white fungussy stuff on the fish you need to do some seroius cleaning of the tank and replace the water a few times. You probably would be wise to strip the tank down and scrub everything. There are medications available at pet shops for fungus.
Yes they can
no
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
Goldfish are all coldwater species no matter what their fancy name. They breed at around 70F so they should be kept under that temperature most of the time. (Between 55F and 65F is OK for goldfish)
There is no record kept of the "oldest Goldfish" but I have known them to live for over 20 years.