black mollies, and their care

Question
Hi!  We just recently obtained two black mollies four days ago.  One just passed away, and we don't know why.  I was told that their water may naturally get a little murky, and to date, it's slightly murky.  We've fed them once per day, and they've eaten all of the food.  Should they have a charcoal filter along with the oxygenation system?  We don't think they've been over-fed.  We need to know why the smaller one died before we can get another companion for our bigger one.  Can you help?  

Staci  

Answer
You may never know why the other died.  He may have been stressed from the move, he may have been sick, it is hard to tell.
I am not sure what you have in your tank when you say oxygen system, I certainly think you should have some sort of filter device that is actually catching the debri in the tank, not just an aerator.
Good luck!