would this method work to pair bangai cardinals?

ok i know about the white thing that makes u know if this bangai cardinal is male or female but it never worked with me, so i was thinking about this method so would it work?



i have a 10 gallon tank that is cycling now, i was thinking of getting like 5 bangai and putt them all together in the 10 gallon tank so they fight until one pair stay alive, would it work?



i know its something mean but i really want a pair :P