Today's invasive species: the water hyacinth.
Native to the Amazon basin, but considered an ornamental aquarium plant, the water hyacinth was introduced to Florida in 1884. By the mid-1950s, water hyacinths were clogging Florida's water ways and interfering with navigation, not to mention displacing the native species. Clean up took millions of dollars, and they're still spreading on every continent except Antarctica.
Guess how many of the species on the International Union for the Conservation of Nature's list of the one-hundred worst invasive species are the result of aquarium and ornamental releases?
A full third! You see, when it comes to aquarium animals and plants, we're dealing with mature adults, and particularly hardy ones at that, since the weaker ones don't survive transport. So whenever they're released into the environment, either intentionally or accidentally, they're better able to establish themselves.
Despite all this, until recently researchers have largely ignored the role of pet fish and aquarium plants when studying the spread of exotic and invasive species. Finally, it's time for some guidelines, especially ones that encourage the trade of less invasive and aggressive species, or the substitution of native and/or safer species that people could grow instead.