The White Amur caper

In 1876, the common carp arrived in the United States and was suppose to provide sport for the angler, a supplement to annual commercial yields of trout, bass, and perch, and was to root out unwanted water weeds from shipping and irrigation canals. It would one day alter and degrade the freshwater ecology of almost all North America. Common carp destroyed prime trout and bass habitat by muddying once-clear waters and often root out preferred shallow-water plants that hold banks and prevent erosion and ignore the nuisance algae's. In the 1960's, a similar mistake was made when grass carp were imported into the U.S. to be used as a water-weed control agent. Grass carp are not true weed eradicators because they prefer the tops of plants and will only attack the roots when other foods are exhausted. This may result in the spread of exotic aquatic plant pests which propagate themselves by fragmentation.