I've had my molly for about a month and she has started to swell up like this. Is she gravid? I have a 50 gallon tank with 3 medium size bala sharks, a 5" common pleco, a 2" albino bristlenose pleco, 5 longfin zera danios, 4 neon tetras (I had nine, but they have neon tetra disease. I am hoping...