You can not keep 6 jardinis together. They will rip each other to shreds. Those arowanas in the video were not jardinis. They were silver arowanas and asian arowanas. Those are much less aggressive than jardinis. I know that you are serious about building this pond. But 9 feet by 4 feet is kind of narrow for a large paroon shark. I would suggest making your pond slightly wider. Groups of asian and silver arowanas will get along fine. Groups of jardinis won't get along. Jardinis are much more aggressive than other types arowanas.