So yea you should line your tank walls with some plants so he doesnt bump into the walls too much. too much collision will cause the tip of the lower jaw to become raw, it might even damage the jaw and break it! Also constant rubbing and abrasion against the side of the tank will cause the barbels to wear away, and not you have an ugly aro. But dont fret because they will grow back. Also DIM THE LIGHTS!! aromwana are really sensitive and skittish so the slightest movements will send them off flying. weigh down your lid and never underestimate what an aro can and cannot jump through. keep your lid COMPLETLY covered. Also putting some other semi aggressive fish in the tank or fish that swim around alot will get him used to constant movement, and will in time calm him down. My suggestion is getting a pangasius catfish. they grow to equal sizes and the pangasius will never punk on him and is a constant swimmer. plus what ever the arowana leaves behind the catfish will most of the time fish off the left overs. enjoy your dragon, they are by far the most majestic of fish.