Can cardinal tetra be kept with Arowana

It may sound crazy, right? But I captured these pics and a video of a show tank in the Dallas Worldwide Aquarium in which an asian red arowana was kept with hundreds of cardinal tetra, a few plecos, and a pair of Thorichthys elioti guarding a brood of fry. I do not know how big the tank was, but judging from the size of the arowana in comparison to the tank, it must be over 800 gal. The arowana was gliding gracefully among the cardinals, and I did not observe any predation. I can't imagine the craziness of mixing fish like this, particularly in a public aquarium. The pics and video were taken many years ago when I visited Dallas, but still puzzled me so I made a youtube for sharing. I wonder if the tank is still there. It was located in the auditorium, not the main display tanks area.



[video=youtube;6AK9WfyTffk]http://www.youtube.com/watch?feature=player_embedded&v=6AK9WfyTffk[/video]

Another factor is that the tank is large, and the fish density is low. Other than hundreds of tiny cardinals, there were only a few large fish that included a pair of Thorichthys, a few large plecos, and a single arrow. It won't work if the tank is small, or the density of fish is high. Just look at the Thorichthys pair. They were able to guard their brood successfully against a much bigger predator, and hundred of cardinals that will not hesitate to prey on their fry.



[video=youtube;RFgUA2ypqjI]http://www.youtube.com/watch?feature=player_embedded&v=RFgUA2ypqjI[/video]