ok so he has been eating awesome since i brought i him home yesterday, and has already made a mountain in the tank, but he looks really grey and his stripes arent as pronounced as they were. yesterday he was dark black and white, now his stripes are barely noticable. is this normal? i swear i watched him change color to bright again and now he is grey again. do they do this? is it stress? i changed the water and fed him.