Bengalli Cardinal - Orange hue ?

[hfp75]

Anyone know what makes a Bengali Cardinal turn an orange color?

pic:
http://i101.photobucket.com/albums/m...ps140525c2.jpg

Its not very visible but its not the nice white/silver that it once was - only about a year old and the tank parms are clean (N03 <5, PO4 <.1) it was once a nice white silver in color but its now turning orange.... its mate is the nice white/silver....

As a Paramedic I was thinking Jaundice but I don't know what that even looks like in fish.

Anyone?