Hi all I have a groups of harlequin rasboras and two of them seems to have some sort of wierd dance. they go side by side, and start swaying their tails and then after thet, they start chasing each other and nipping each other. is this some sort of agression? I only have three in the tank so far. Is it possible that this agression is because there aren't that many females to balance out the group? pleaze help!