Help! Dueling Rosy Barbs

[Cherry Barb]

I have two pair of Rosy Barbs in my fw community tank. One pair is long finned the other short. I have had them for several months and they have been very peaceful fish. This morning however, the males are going at it. They will be this fighting swirling mass of fins, then take a break, breathe really hard and do it again. I can't tell who is actually the aggressor. They seem to go at each other at the same time. Everything I have read says they're usually peaceful fish. What do I do?

Thanks,
Rose