We bought a 10 gallon tank 5 months ago for our 3 year old daughter. We bought 2 Mickey Mouse Platy's, not knowing if they were male or female. I noticed after a few months that one was chasing the other and would not leave it alone. I researched and found out how to tell them apart and realized we had a male and a female and that it was recommended to have 2 females for 1 male so he doesn't chase her to death. The female we had is very small compared to the male. Anyway, we bought another female, she was about the same size as the male. He then left the small female alone and he swam with the new female all the time. It's been just a few weeks since we bought the new female, and 3 days ago I found some fry in the tank. I have no clue if the small female gave birth to them or if we had bought a pregnant female. I separated the fry in a floating fish hatchery to protect them. Now the male attacks the small female if she comes out of hiding and won't leave her alone, yet he still swims with the new female all the time. As soon as he sees the small one he attacks her until she hides again. She misses feeding sometimes and I wonder why he would pick on her. Does anyone have any ideas or suggestions? I don't want him to kill her Thank you in advance!