As with any fish, keeping the tank in a location where they are safe from being bumped into, or stirred up unnecessarily, is wise. You need to keep the top covered and held down as well, since they are excellent jumpers and otherwise may wind up outside the tank. 55 gallon might be sufficient for juveniles, though 150 gallon+ would be advisable as they mature and grow larger. Remember, moving the tank is not going to be easy at all, so better planning now will save a lot of time later and spare the Asian Arowana a shocking experience