Elvis your chinese algae eater could be to blame. they get very nasty and with just one or two attacks, can put holes in fish very quickly.
as a beginner with a new tank, i would stay away from livebearers entirely. ie your mollies and swordtail.
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46G Bowfront: 1 large snakeskin gourami, 1 blue gourami, 2 pearl gouramis, 3 yellow honey gouramis, 12 black neon tetras, 1 albino pleco. All gourami's are female as far as I know. 
Lighting: 78 Watts (1.7 wpg) T5HO
Plants: Java Moss, Flame Moss, Marsilea Minutia, Marsilea Quadrifolia, Staurogyne sp., floating Myrio Simulan.
Substrate: 80 lbs Eco-Complete.
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