Turning orange?

[applechickbsn]

Question...
What is it in a tank that makes the white (silver) parts on fish appear to turn orange?
ie: Zebra danios, normally a pretty silver and black, now look orange.
Angelfish....normally a marble, now appear to have turned orange on their "Top" part of their bodies....

 

[OrionGirl]

If these were juvenile fish, changing color can occur. Otherwise--what's your lighting and deco look like?