About 3 months ago, I got a 10 gallon tank (Waited 2 weeks), then stocked with 4 platys that had previously been in a 2.5 together for about 2 weeks (I believe they are all male. I have one blue platy, one gold twinbar, one marigold variatus, and one sunburst platy). I also have 3 nerite snails and a gold mystery ((One black racer nerite, one smaller tiger nerite, and unknown nerite, and a gold mystery snail) Two are about 1-1.5 centimeters, the other two are about 2-2.5 centimeters) I recently noticed the gold twinbar and sunburst attacking each other, and they were quickly joined by the marigold, all nipping at each other. The twinbar and sunburst were beginning to tilt, the twinbar from possible minor injuries, the marigold from an undersized fin. I immediately removed the sunburst and marigold, putting them in separate glasses out of sight of one another with a lid to prevent them from jumping out. The twinbar and blue platy have been fine in the tank together, not attacking each other, just swimming around the tank happily like nothing ever happened. What is going on? Is the blue platy a female? Why are they attacking each other? they have been fine for 3 months!