GSP Problem

If he's sleeping or eating, or you have a dark colored substrate, it's normal.

Kim

possible lack of nutrients. i know that GSP's wash out when they sleep or can change color when stressed. but if he's like that all the time i might start to worry. what's the water perameters? do you have hiding spots for him? usually by having them in 1.005 SG will help their color, although as they mature they will need higher SG and eventually full marine water.