Arowana not eating

[Spakase]

I'm having the same issue with my new 8 inch silver I got yesterday. It's in a grow out tank (55 gal) with a three inche tiger oscar, 5 inch clown knife, 5 inch pleco, 4 inch pictus catfish, 5 inch African knife, two 5 inch bala sharks, and two 3 inch red belly pacus. Community fish from this tank will go to a different 55 and semi aggressive and aggressive will go to a 200. But could these fish be stressing the aro too?

Nope, those fishes are smaller than the silver and not likely to bother it.
It's the bioload you need to be careful about.
Agree that it takes a while for a new fish to get comfortable with it's environment and once the silver does so, it will eat.