Cory Changing Colour?

[xamy_valox]

Hi there, I have mentioned in a different post that one of my Leucomela cory's has become considerably darker lately. I will try and post a pic tomorrow of what it was like, and what it is now, but just wanted to make sure this was normal?
Tizer has said it may be something to with different sexes but just wanted to see what others thought?
My other Leucomela is still a pale White colour where as my other slightly larger one is a much darker grey colour. They were both bought at the same time and I've had them for a couple of months now, water stats are fine but will post more accurate results tomorrow as I'm not in natural light.

 

[Caprichoso]

Just before he died, my 12 year old cory turned very dark grey. That being said, many fish do darken up when they are breeding but I have yet to notice this with any of my corydora. I hope all is well with yours.