That is why i compared them to bala sharks. I am also not sure where you get 60 inches from, a 12in oscar in a 48in x 24in aquarium has 4 times body length of space side to side and 2 times body length front to back, a 5 inch fish in a 20in by 10in aquarium has 4 times body length side to side and 2 times body length front to back. The point of the oscar comparison is that most people think a 120 gallon, 48in x 24in aquarium is acceptable for them.
A 5cm neon in a 60cm tank has 12 times body length of space, if that is the minimum for a neon than there is no reason that a bala shark should not have a similar minimum of space which would be 4m and most people think it is completely fine to keep bala sharks in much smaller spaces than that.