Each man kills the thing he loves!
Switch them around.
Put the female back in the 240 and the male in the other tank.
This way she will be able to claim the territory as hers and hers alone.
Leave it like that for a couple of days.
Then introduce the male in the 240.
This could put a damper on his aggression.
You could also consider using 7-8 tiger barbs as "dither-fish".
Beautiful fishies who can hold their own against most other species.
Biotopically correct as well!
