Animals and plants originating in other countries and ecosystems can transform their new environment and even displace local species, warns Venezuela's National Office of Biological Diversity. Venezuela is ranked sixth in the world for greatest biodiversity.

But some foreign species, such as trout, have reduced the populations of native fishes in the country's Andean mountain rivers.

Another case is the 'mojarra,' a small fish native to the Maracaibo lake in the west, and now found in nearly all rivers in northern Venezuela.

The aquatic 'pipa parva' frog, originating from the same lake, has become a plague for aquiculture because it feeds on young fishes, diminishing the population that reaches full size.