I acclimated to accept a 125 gallon alloyed south american chiclid tank. A lot of these angle can be mixed, but accomplish no aberration even a 55 gallon tank is not that big to these fish. I apprehend that you accept gouramies with your chiclids, unless there ample gouramies they will eventually be outgrown by your chiclids. Bala sharks are not an aggresive fish, they may be afraid by beyond fish.