I just go some fish from a friend of mine, and they were pretty healthy, but one female molly had a bump on and around her left pectoral fin. She was hardly swimming and just laying on the bottom. I got her out of the water and put her into a lid with water so she could breathe, but i could look at her fin. I thought it was a worm, but i poked it with a needle and puss came out. I endede up haveing to take off the fin ( i work in a vets office and the fin was completely abcessed.) I gave her a salt bath and put her in a breeders net to rest. That was last night. She is still alive this morning, doing much better than last night before her "surgery." She is swimming around apperently happy. If anyone have experience with this, or any suggestions they would be greatly appriciated.