Hi. I recently added a 5 inch naso tang to my 125 gallon reed tank he has been in the tank for a week now. He grazes on the rocks and just pecks at algae strips and occasionally will take a small bight. I'm worried cause his stomach area seems to be kind of thin. Any suggestions? He doesn't seem stressed he is out swimming around and is the biggest fish in the tank. Just worried I don't want him to die especially if there is something out there he would like to eat.?