"Morten" wrote in message ...
I did the same 'mistake' once and bought a couple of very cute and black
orange gold fish once and thought that they would stay that color. They
dont, they just look funny until they get their 'normal' orange color, but
when I started with the goldfish's I didn't know that...

I think Calico Fantails retain their mixed colorings into adulthood.

Would a 2mm-wide black lining along the entire edge of my orange fantail's
caudal fin and a 1mm-wide black lining along it's dorsal
fin be able to disappear in just 3 weeks as a result of maturing?
I though these color changes take quite a bit of time to develop.

That sounds like the fish has recovered from amonia burn in th past, you
sometimes see that if the edges of the fins has become damaged by finrot or
amonia burns, when the tissue grows back it starts out black and then turns
orange over a couple of weeks...

Wish I had known that a month ago. But things look good in my tank now.

My 2nd fantail (Clinton) is completely orange now and looks just like my
first fantail (Carter).

You named them :-)

Yeah, and my Red Cap Oranda is named Reagan
The Republican is not giving the Democrats a fair chance at the food at feeding time
But the Democrats have been known to gang up on the Republican.