disease in Male Beta

Question
My fish tank is 18 gallons in size and it contains a total of 10 tropical fish. The PH is at acceptable levels and the water temperature in the tank is approx. 78 degrees F. I have had a male Beta (approx. 1.5" long) for over a year, and he has generally been active and healthy. In the last 2 days, however, I have noticed that his anal fin appears slightly ragged and torn (not due to any damage) and his abdomen appears to be bloated.  He is still active and eating okay, but I am wondering what disease he may have and how to help him.  

Answer
Hi Avery: He may have an intestinal blockage, internal parasites or a disease called dropsy.  Dropsy is distinguished by scales that stand out from his body like a pine cone.  It is a disease that is extremely hard to treat and usually is fatal.  If he has an intestinal blockage... then you can feed him brine shrimp because they have a laxative effect.  They will help also with internal parasites but he will also need a medication to cure the parasites.  Let me know which best describes him.  dave