They should eventually stop but if they get to agressive you can cup them and rearange and re release. The usual ratio is like... 4 or 5 for a ten gallon. You can also add a couple more girls. They usually fight less with more gals and your tank is big enough to get a few more. If you get a few more girls recup the others and rearrange the tank and release them that way. They fight because they try and establish a pecking order. You will almost always have a few nips out of the tails here and there though. Is there one picking worse than the others?
The agression also depends on how well packed your tank is with plants, hides, etc. You need them on all levels (at the bottom, middle, and even at the very top of the water) and all throughout your tank.