sounds like it's scared, begging for food, or possibly the water.
fish tend to scratch themselves and dart around the tank when for example, you do a dangerously large water change. not sure about aros.
both my silver and jardini are scared of the colour yellow, and my silver is scared of any object hovering above him. either way when they're scared they exhibit similar behaviour that you described, plus some jumping. keep in mind that when arowanas sleep they still swim around with their eyes open (cant close their eyes obviously) and it appears that they're awake, so it may be that you're startling him.