My goldfish first had white spots, now the tail veins look red. Any clue?

I'm not for sure if this is an illness or not. I've got five gold fish (Not the kind with the flashy fins but more lake fish like, if you can understand) and out of the five, only one is gold. The others I either got white or were red and white and turned gold... Well, except for one. One of my now white fish was gold when I got it and then it slowly turned white. So, I don't know if the fish is sick, but if it's like mine it could just be a change of color...