Sick swordtail--possible constipation?

whenever u have a diseased fish, u need to have aeration when not provided it could lead for further problems......i correctly couldn't find out what exactly the disease is but i can tell u one very important thing u can do.....get some potium permanganate(easily available at medical stores) and add a little quantity to Ur water, it acts as an anti-bacterial medicine and would cure almost all fish diseases....even when ur fish is battered after a fight u can use this to heal it quickly...