I have 2 Black skirt tetras that I just recently added to a 10 gallon. I noticed this morning that one of the tetras skirt was no longer black...but about 3 hrs later, the color was back?...Any idea of what causes that?
Stress often causes colors to fade on a fish. Also, while the lights are out, if the fish is 'resting' their colors often fade to make themselves less 'visiable' to larger fish.
I've found the same thing happen as OrangeCones said, all my fish have faded out colours if they've been sleeping or if the lights are out. I've found it takes a lot of stress to make them lose their colour also.
Sometimes they will also have more "washed out" colors if all the decor / substrate is light, whereas in a darker setting they will have darker coloration.
