Bala Shark is eating my Golden Gourami!!!

Hi

I am a newbie so any help would be appreciated.

My small newly set up aquarium has 6 neon tetras, a few small catfish,
two golden goutami (5cm) and one bala shark (4cm).

The bala shark has started biting the lager male gourami and has
opened a small wound on the gourami's back, which the bala now picks
at constantly. The bala doesn't bother wih any other fish in the tank
and is otherwise a great fish to keep.

Do I need to get rid of the bala?? Or is it the male gourami?? Will
this be resolved if I get another bala (I have been told they are best
kept in pairs)??

Any help much appreciated.

Kev