Why do we classify lionfish populations near the eastern united states as an invasive species? what suggests that these new populations are not an expansion of the lionfish's natural range? view available hint(s) why do we classify lionfish populations near the eastern united states as an invasive species? what suggests that these new populations are not an expansion of the lionfish's natural range? lionfish are native to the tropical pacific. there are no natural water routes of warm water between the pacific and atlantic oceans. lionfish are native to cold waters near the tip of south america. they could not survive in the warmer waters between their native areas and the colder waters of the east coast of the united states. so, it is very unlikely that these south american populations naturally spread north. lionfish are not good swimmers and have no other mechanisms to spread their populations over great distances. lionfish eat only a few specific types of algae that live in isolated regions of the pacific. if lionfish spread much beyond their native pacific home, they would have nothing to eat?