Bro, arowanas dont like strong flow too much, especially blacks and silvers, when they are bigger its less of an issue. Plus, parrots are retarded fish, it will get blown around the tank :lol:
If you want a cool river effect slope the gravel from one side to the other, use rocks and spindly driftwood at the shallow end, leave the deeper part clear, simulate a half cross-section of the river. Just a thought.