If I am going to be feeding them shrimp and any other sea food are they okay to buy at any seafood store and drop in?
***Yep. I buy frozen. Thaw and drop in. Needless to say, cut in sizes they can swallow, otherwise they will spit out. Freezing kills all parasites (does not kill bacteria but it's usually ok)
Do I need to get pellets and such specific specifically for arowana or are any ok?
*** Different people will say differently. I think any are ok. My silver aros went for all kinds of pellets - catfish, koi, gamefish pellets and have been fine.
Is there any specific type of ingredients to use or avoid?
***Make sure the foods are whole and uncooked, unseasoned, unsalted, etc. No spices. Just came from the ocean and frozen.