Help! my green spotted puffer has just turned brown

Question
Hey David, My name is Emma.  I just recently got two puffer fish.  My question to you is that one of my green spotted Puffer fish just turned into a really dark brown color.  What does that mean.  Is it because of certain foods im feeding him? I think they were called ghost shrimps or maybe something along the name of brain something?  He is really down and is not responsive to my hand wave when it usually gets him up and swimming.  Every now and then he will be swimming, but im really concerned.  This fish is usually really happy and love to eat unlike the other puffer that just lays around.  What should I do?

Answer
Hello Emma:  Fish turn colors for a variety of reasons... sometimes it is a dietary issue, sometimes it is due to aggression in the tank.  Puffers are predators and as such they will turn colors to help them blend into their environments.  Puffers also find a place and sit... they wait for fish to come by that they can eat... if you are seeing no sign of disease you can try to feed him.  Is he eating???? dave