The sand def makes their dark parts darker... which allows the stripes to stand out more. Pretty much why I did the black, not a fan of the lighter coloured ones.
X2... don't know if its the picture or what, but the stripes do seem very well balanced... wonder what would happen if it was a light substrate in there...
Nice lookin' Fahaka!
Darker substrate for sure brings out darker colours - Lighter substrate will make his colours lighter, as for my mbu, we have black gravel and he's bright as can be, so not too sure if this goes for all puffs - Certainly the fahaka though!