@Feryll - The tropical fish like mentioned in this article couldn't survive in most of the waterways in the United States. The cold waters wouldn't be ideal for them and they would most likely die if they couldn't find warmer water.
However, I think I know the fish you are talking about. They are carps that originated in China I think. These Asian carp are invasive and they do leap out of the water, but they don't actually glide long distances like the tropical flying fish.
The Asian carp are easily startled, so if a motor boat is moving through the water where the fish are swimming then the fish will often leap out of the water to escape the sound of the motor which they see as a danger.