Bala sharks are schooling fish so they need groups of 6+. They also grow to 12 inches each. A school of bala sharks should have minimum 150 gallons.
Elephant fish grow to 12 inches I think. Regardless, you need a tank over 150 gallons, and with one that size, why would you want small fish?
Balas can be kept with small fish, but the fish needs to be larger than their mouth.