Florida! Make sure you get the propagules--those should be legal to collect in many areas--it is illegal to collect mangrove trees.
I have a little white mangrove going in my new 11.G setup. It is the large-leaved plant second from the left in this picture.
I have found these to be slow-growing and not very hardy. Several of the ones that I started died after a time. But they are cool little plants. They grow well in riaprium planters and do best with a rich soil-based gravel and root fertilization.
I hope to work on the underwater area soon. I have some nice stems to put in there.