Silver carp are native to Southeast Asia and east Russia and were intentionally introduced into the United States in 1973 in an attempt to improve water quality, increase fish production in culture ponds, as biological control and as food fish. The fish now occurs in at least 18 states and is naturally reproducing. Both the silver and the bighead carp compete for food (zooplankton) with native fish. Black carp are native to Asia and eastern Russia. These fish were unintentionally introduced as a stowaway with intentionally introduced grass carp. Black carp now occur in at least 5 states. Black carp may reduce populations of native mussels and snails through predation and negatively affect the aquatic ecosystem. None of these species are currently found in Wyoming, or Montana.