I have a black molly who is about 2 weeks old whos back tail fin is clamped.. It was fine last night then when we got up this morning it was on the bottom of the tank like it was dead or sleeping although because we thought it was dead when tring to use the net she tried to swim away. I have done a 1/2 water change and put salt in the water this morning. DOes anyone have any idea y this is happening... Please help...