IMHO, It depends alot on what color substrate that they are housed with. Dark=dark, Light color substrate=light color fish. I personally think that the pattern gets overall darker with age. When they are smaller/younger the Aimara Wolffish uses its pattern to hide in more shallow water to keep from being prey for larger fish ,including larger Aimara Wolffish. Once it gets larger the pattern gets darker overall , because they inhabit deeper darker water and don't have to blend in with the leaf litter and other structure that is in shallow water that hides them when smaller. Just my opinion. Thanks