Green Barbs - Fighting or Mating?

[eeyipes]

I have 5 green barbs (getting more tigers or greens soon). I've noticed the two largest occasionally face each other nose to nose and dance in a circle facing each other. There doesn't seem to be any nipping or damage done. Are they testing dominance, or is this male/female behavior? How can I tell the difference between the girls and the guys? thanks

 

[rufioman]

Establishing dominant role in their little society if they are fairly new to the tank or have reached breeding age. If no excessive damage or isolating then it is most likely courting behavior.