[Pavel Chaloupka]

Yeah my young Paro males do that too. Looks exactly like what Nannostomus males do. [video]http://https://www.youtube.com/watch?v=Vyoi4ITBHKE[/video] you can see it from like 0:26 on this video with N.mortenthalleri. I think its kind of messuring the strenght and size by pushing each others bodies without actual fight. I have seen that twice so far. The one male that seems to be adult already shows his normal coloration or becomes slightly paler, the smaller and weaker one become pale at the very start of it but did not run away. Kept resisting for like 30 sec before running. I have only one male realy displaying infront of females so far, but than he shows typical head down postion. My plan as soon as I obtain the stuff for it is to put a web cam infront of the tank and find a server where I could stream the tank continuously. This way we could see behaviour of the group and may be get more info on how fish interact within a group in bigger tank. Becouse every time I aproch the tank they mostly gather on the feeding place and do much else.