What I did, was put 6 small banggai's together, 2 would pair off and fight all the other 4 away, scoop those 2 into a seperate tank, and the next 2 would pair off. You know they are a pair because both would stay towards the middle of the tank, while the others would cower into whatever corners they can hide in. Then my last 2 paired off as well. Guess I just got lucky to get 3 males/females.