Tennessee Aquarium, arguably one of America's 5 best aquariums, opened River Giants recently, and according to "Connect", the AZA magazine, 87 tons of concrete were removed from the huge Gulf of Mexico/Mangrove tank. Some of the fish on exhibit: arapaima, barramundi, Australian whipray, lake sturgeon, redtail catfish, giant pangasius catfish, marbled eel, blue catfish, alligator gar and wallago.