Salvinia and many other plants come from tropical fish hobbyist. I hobby in marine and African Cichlids. These two hobbies do not have live plants in the aquarium. I have seen signs posted at public boat ramps that ask you to check your boat trailer and motor for feral aquatic plants. I have seen the state spray aquatic vegetation and they kill everything with that spray. There is a white Amur Carp that is known as a grass carp that can do some serious eating of plant matter. Before they stock them in a lake they neuter them so they do not take over. This is better way than chemical.
Salvinia (Salvinia molesta)
White Amur
Other Names
White Amur, Waan Ue
Description
Ctenopharyngodon and idella are both Greek words, meaning "comb-like throat-teeth" and "distinct" respectively. The grass carp is one of the largest members of the minnow family. The body is oblong with moderately large scales, while the head has no scales. There are three simple and seven branched rays on the dorsal fin. Grass carp are silvery to olive in color, lacking the golden hue of common carp, and they have no barbels. This species typically reaches sizes of 65 to 80 pounds in its native habitat, but individuals approaching 400 pounds have been reported.