Why is the black disappearing on my red Oranda goldfish?

[Chiquita]

I bought two Oranda goldfishes with black on the tail, fins and his lips were lined black. Well one of them is all orange already I was SURPRISED and now I am paying attention to the other bigger one and the black is disappearing on him too. What is the problem??? Someone please help!!!

[John]

Hi Chiquita, nothing is wrong-please don't panic!! All you are seeing is simple genetics because the pigmentation in Goldfish is extremely unstable. The black lines are particularly common on baby fish & often grow out in a few months. 3 years ago I got 2 Lemon Comets, one of which had the same black stripes on all his fins & tail-so much so that I called him Mr Blacktail! Within a few months he lost the black completely & was all yellow for a couple of years, over the last few months he has started to lose the yellow as well from below-so much for naming my fish according to their physical attributes!!