It really looks like it could be a tumor. We very recently changed the water and cleaned the tank. It is a 30 gallon tank - probably not big enough for her, as she is about 15" long.
Our 5 year old Oscar hasn't eaten for about 2 weeks. She has a large swelling on her underside and we don't think she is eliminating. Now her eyes are cloudy and she is getting pale. What can we do?