I have 6 neon tetras and 3 platties. One of the platy was nipping fin of the other two yesterday, almost nipped the whole fin, so I removed that platy and put it in a separate jar. But while that one platy was out, the other one started nipping the nipped one. I thought maybe because they are only two, that's why its picking on other one. So after half an hour I put that fish back from a jar to aquarium and I think they did not have a problem again. I don't know if its going to act up again or not, but I want to know why they are doing this. And by the way, the temperature of the aquarium is apporximately 82 to 84 deress. All three of them are male, by the way. I am thinking to give these three away and getting more tetras. Any suggestions? If I add mollies, will there be a fin nipping problem?