I saw a travel docu a few weeks ago regarding this menace in the Caribbean. Fortunately, it is good eating, rather like snapper, but has few natural predators, while being very predatory itself. The countries of the Med need to do what they can to eradicate this menace.
http://www.dailymail.co.uk/sciencetech/article-3662481/Going-holiday-Deadly-lionfish-invading-Mediterranean-rising-sea-temperatures-warn-scientists.html