Why do Goldfish change colour?

Sunshine my Red Cap seems to be turning into a red and white, and when I was younger Chino (named because I had a Red Cap named Cappie), turned from a gorgeous Chocolate colour to a bronze/gold, why do they do this? Also I'm sure my red Oranda is actually a Red Fantail, coz he still has no growth on his head

More often than not it is simply down to genetics and is nothing to worry about. When Red Caps get beyond the juvenile stage they are usually completely white in body with only the 'cap' that is red.

Goldfish can be weird. I had a Black Moor that eventually went orange and looked like a standard Fantail.

Thanks, its kinda annoying though coz I specially wanted a Red Cap, because I think their gorgeous, and Cappy was my fav fish, plus I thought a Red and a Red Cap would look nice, and love Orandas, and I've ended up with a fan tail and a Red Cap thats got red extending down his back and a bit on his dorsal fin, and extending down his face, so I really think soon that Star wont really be able to be called a Red Cap will he? oh well, its still nice to have a tank again,