Black Molly Acting Funny

[RexDarr]

Hello everyone!
I've had my 20 gallon set up for just over a month and a half. So far I've had thriving live plants, another molly drop a huge batch of fry (25 or so. Only 2 survived. I used some to feed my other fish too), and everyone is happy!
I have 3 female mollys, a male, and 2 fry too young to determine the gender.
Everything has been going great until I could only find 3 fish. I searched everywhere for the black female molly. Eventually I found her in a corner of the aquarium breathing heavily and all her fins out. She swims around a small bit then returns to the bottom breathing rapidly and almost shivering. She doesn't look pregnant but I know my male was getting jiggy with her before. Could she be getting ready to give birth? I've been watching her for the past hour and she hides somewhere, goes swimming around for a little bit, returns to the hiding spot, then swims to another close by. She spins in circles from time to time but stays breathing heavily. Her fins aren't clamped and she has been eating. She looks like she's shivering but the water temperature is around 76-78F. I added a little more aquarium salt into the filter hoping it will calm her down.

Sorry for the long winded message. Could she be pregnant? She's a black molly so I can't see a gravid spot. She doesn't have a big belly either. What are the normal "routines" for a molly about to give birth? What activities do they do? Behaviour? Things I should watch out for?
(The one that gave birth in my tank did it at night when I was sleeping. She wasn't fat either and was swimming around with everyone else when I went to bed)

[henningc]

Sorry it took so long to answer you. It sounds like she might have dropsy. Look down from above and if she looks like a pinecone put her down. Otherwise she has swim bladder issues. Feed some blanched shelled green pea and give her a bath in epsion salt.