Do his scales look slightly puffed, like a porcupine? If it's dropsy, you can add a "Tank Buddies" product to the hospital tank and hope you catch it in time. Just read the back of the boxes. It says which one is for dropsy. Do you have any salt in the hostpital tank? Mollies can be brackish, so I strongly recommend adding some sea salt to help speed the healing process and destress the fish. You can use a Hydrometer (a plastic thingy) to monitor the salinity (how much salt it in the water). I would add salt till it reads 1.002 at first. Try not to change it by more than .002 per day. I love my mollies too, and this is how I keep them healthy. Good luck!
