The arrival of the Indo-Pacific lionfish in the Caribbean has been major source of concern flagging once again the increase of alien species throughout the marine environment. One element of the narrative was that since the Caribbean was devoid of natural predators for the lionfish its rapid expansion across the region would decimate reef fish populations. This remarkable video [be patient with the horribly long starting credit] shows a grouper stalking and corralling a lionfish prior to eating it. Whilst N = 1 doesn’t provide conclusive evidence the clip shows some remarkable behaviour and that at least one of the Caribbean’s grouper species can tackle lionfish and provide some natural resilience to this species.

http://nypost.com/2015/02/26/lionfish-stalked-and-devoured-by-grouper-in-shocking-video/
http://www.wri.org/atlantic-and-caribbean-lionfish-invasion-threatens-reefs