I have one female platy and 2 males. When I first got them the males didn't fight about 6 months ago. Now it's war one has a missing fin the other has half a fin. I bang on the glass works sometimes but the next day or in a few hours there fighting. What should I do to tame them. I'm thinking of bashing them aganist the glass and keep the one thats still alive. Plus sometimes my betta joins in. I have a 40 g with some plants.