I hope they dont the shop i got them from is a good store who seems to take pride in there stock. Not that it will make an diff to if there colours fade or not. The markings on the 2 i got and the rest they had were all very white and bright. There was 2 in the tank but that had no markings and had a hint of like a iredecent blue or purple to them. I thought this to be very strange but i am new to the world of fish.