I’ve grown somewhat accustomed to seeing these brightly-colored wayward fishes in my underwater wanderings, so when I happened upon a tiny lionfish clinging to a wooden piling along the south shore of Long Island in September, 2001, it took a moment for me to fathom the implications. This was not just a stray from the tropical Atlantic. This fish was way off course.

More... (http://www.advancedaquarist.com/2006/6/aafeature)

I'd ran across this NCCOS: News - Lionfish Discovered along the South Atlantic Coast: A Curiosity ... or a Wake up Call? (http://coastalscience.noaa.gov/news/feature/1003.html) a while ago.