Pablo and Mercedes...

Been awhile since I posted these two, and since they both shed within the past 4 days, I took a few pics during feeding tonight. I'm still amazed at how different they look. They're 1 year apart in age (3 and 4 years old), only 500g different in weight now (Mercedes caught up well in the past few months), but Pablo is still so orange and blank with a crisp white belly while Mercedes is very patterned, more brown, and more iridescent. I have paired them twice so far but haven't witnessed any breeding activity -- more to get them introduced to each other so that when they're together for the long haul, it won't be a big change. Since putting them together, Mercedes has developed a big color change -- she's gotten these bluish gray sides which makes her pattern more evident, and now she is REALLY rainbowy. She just shed 2 days ago so it has nothing to do with being blue. She just looks so different now -- I thought that as she gained weight, she would dull out and look more like Pabs...but she's gone even more drastically colorful. Thoughts?

Pablo:





Mercedes:





This was Mercedes just 2 months ago...:



Any ideas on what caused her color change?