AHH. Finally. Someone else with this problem. well, I certainly think it is a lack of oxygen. What other fish do you have in the tank?
I have a tank where my poor diseased molly is and the other fish(4 two spot barbs, 3 long finned leopard danios, WAY too many guppies, a pair of dwarf gouramis, 2 otos, 1 clown loach and one leopard cory.) are is happy as could be.
I think mollys are very flow-needing, per se. This guy has been diseased since I put him in my 55 gal. He has some fungal disease that starts out in the eyes, then moves to the body. I'm keeping the body clear of it, but it's hard to keep the eyes clear. This other tank (not the 55) has very poor flow, but it has lots of live plants.
Well, getting back to your question, yes, add like a bubbler or another filter. You didn't say what kind of filtration you have.
oh ya how long have you had this molly, how old do you think she is? she might just be getting old and ready to die. My old guppies do that.
hope I helped! reply soon!
guppy girl