Anatomy or disease?

[law15]

I am hoping that someone with experience can identify something that I have noticed recently. I have 8 discus in a 110G planted tank since November. Everyone is doing great and now are 5-6 in. long. 2 days ago I noticed that a red turk has what appears to be a small indentation on both sides. It is just below the lateral line at the end of the abdominal cavity, or just about where the tip of the pectoral fin could reach at rest. It is smooth with no evidence of ulceration. None of the other 7 have this and the fish in question appears quite healthy. He is eating well and is one of the more aggresive in the bunch. Sorry I can't post a picture
Any thoughts????

[Carol_Roberts]

Does he shimmy a bit too? I'm guessing he overate and is probably constipated. Epsom salt at 1 teaspoon per 10 gallons should do the trick (unless it is a bacterial infection). He should be better in 4 hours, if not you can redose the epsom salt. Normal water changes will remove it from the tank.

[law15]

Thank you Carol, You were correct since he looked better in the AM. I am embarrased that I never noticed this before :-[
I appreciate the polite response to what must have seemed such an obvious answer. Chalk it up to newbie anxiety.
LAW