Help with my Balloon Molly

Question
I just bought three Balloon Molly's yesterday at Petland. The woman working there said that they were a fresh healthy batch. I brought them home and they were fine, then this morning I noticed that my black female was lying on the ground. And when she moved around the tank she didn't use one of her fins. The fin that she isn't using looks smaller than the other and has a white tip on the end. Later on today my male molly stop using one of his fins as well. He isn't lying on the ground but he is swimming slowly and around the bottom. My other female is swimming fine buts seems frantic. When I fed them they all ate but then my black female laid back on the ground. I think it might be fin rot but I'm not sure. I bought aquarium salt and Melafix that I added to the tank and before that I did a 25% water change. Do you know if it's fin rot? If it is, am I doing the right thing?

Answer
Hi Mackenzie,
  Fin rot isn't something that has that effect.  Fin rot occurs when a fish rubs its fin on something and in essence bruises it.  Then the tip of the fin can appear damaged and wear away.  It would not cause a fish to stop swimming.   

  It sounds like there is something wrong with your water.  
I assume that you have a heater and the temperature is around 80oF in the water and that you have a filter and an airstone both working properly. Is this the case?

  When you put the water in the tank, I assume that you treated it to remove chlorine, right?

-- Ron
  rcoleman@cichlidresearch.com
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