<---- Look over thar!
I have a 200 gallon tank. The size of the tank is more important for the arowana, 7 feet long is a good starting point. The bass, depending on what species you get, get pretty long as well. It's best to research what species you want, but for just those 3 fish, I would say a 200 gallon is a good place to look, but footprint is more important. If you wanted more bass you should probably look at a 300 or bigger. Most get really large and they like to be agressive.