Its not so much that a gf loses its colour, it is that a gf feels more
comfortable with a darker background. Ages ago when i had white sand in my
tank, the fish were acting all paranoid and weird. I changed to bottomless
(it was a black pane of glass) and the fish acted much more comfortable...

The reason for putting black bottoms in tanks is the same reason alot of
hairdressers wear black aprons, to emphasise colour.
"Gfishery" wrote in message
...

"Gio" wrote in message ...
I have six goldfish living ver y happy in a pond i have a eight month old
comet that is loosing his orange markings and going white can any one
tell
me why?

There is a belief that gravel color and aquarium lighting have a bearing
on
the fish's color as they mature.