Yeah for sure as do33ie says Arowana are not the cheapest fish to keep and it's only going to get more expensive as it grows and needs more food & bigger tanks.
If it's making a mess with the Food sticks try breaking them in half and just throwing in smaller portions at a time. Let them eat each portion then throw in a few more. With it's poo I would just be monitoring it; white, normal shape poo might just be reflective of eating white shrimp, or maybe even indigestion -- but if the white poo gets stringy it could likely indicate a parasitic infection and you would need to take treatment actions. But doesn't sound like that's your current situation.
I feed pellets side by side with either frozen shrimp or fish, so my Aros poo is always the same brown/reddish color. I would like to expand their diet with insects but I'm paranoid they will stop eating pellets and only want to eat the tastier superworms, crickets, etc. so haven't gone down that road yet.