It seems that my guppy has fin rot. At least I think its fin rot... none of the others have been picking on her and the shredded parts have a white outline. All my fish have been acting sluggish so I tried to lower my ammonia and they seem to be happier, accept for the "infected" fish. The others don't have any signs of fin rot. I have some left over bettafix so I was going to try it but not before I know it's safe.