I do not know the name, but it appears to be a terrestrial plant. It will look good for a while, but eventually rot in the tank. It is likely a "semi aquatic", which means it would live along shore lines where it would be out of the water at least as much as it was in it.
It should make a lovely houseplant though. And fish tank water is THE BEST source for watering house plants. You could even place it on top of your tank. But, personally, I wouldn't leave it in the tank.