Dog Faced Puffer Turning Black

[Fishboy1981]

I have had this dog faced puffer for well over a year now. He is a very pleasant little fish. He is normally a light grey color with a few black specks and can change his skin color sometimes to match his surroundings. Over that past 1.5 weeks or so he has been getting blacker and blacker. He is almost totally black now. He is eating fine, swimming around fine and water conditions are good. Any Ideas whats going on?

 

[Lynden]

I had FW parrot cichlids go from orange to a deep, velvety black in a few weeks, then back again. Arothron (to which the dogface belongs) are known to occasionally change colours. In many cases it is not clear why the colour changes but it may have to do with diet or simple change to adulthood.