Sick Naso?


Reefing newb
I got my blonde naso last Friday and ever since then it's been healthy and swimming around just fine. Today I noticed it swimming a little strangely, sometimes at a 45 degree angle but not sitting in one spot. Now, later in the day, it looks like the stomach, the area just below his fins, may be swollen up a bit. But he's still eating which is strange. I have a seaweed strip on a rock and every day he nips away at it throughout the day until it's gone. The same today, it's about half gone now. I also gave it Mysis earlier which it ate up. I fed it that yesterday for the first time and all looked good. I have also noticed when it goes #2 that it isn't stringy like most fish do, it was kind of scattered about. Not how to explain it but sort of like if you sprinkled freeze dried brine shrimp in the tank. He's the only fish in a 180 gallon tank. Am I overreacting to a fattening fish or is there something to worry about? I'd post a picture but it's still timid when I go around the tank let alone with a camera up at.