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 to replace these with more danios), 6 albino cory catfish, 3 dwarf gouramis, 2 male and 2 female millennium rainbowfish, 2 adult and 1 baby candy cane tetras, and finally 2 mollies, one of which is the one pictured above.