Black carp (Mylopharyngodon piceus); silver (Hypophthalmichthys molitrix); Bighead (H. nobilis) and grass carp (Ctenopharyngodon idella).
The latter three species were released in the U.S. from the 1970s through 90s for aquaculture and/or pond application; Bighead, silver, grass, and black carp are native to Asia. Grass carp. All four species escaped into the Mississippi River Basin and spread quickly. Asian carp pose the greatest immediate threat to the Great Lakes ecosystem.
Asian carp can grow to large sizes: some as large as 110 pounds, though the average size is around 30-40 pounds. Bighead and silver carp are voracious eaters, capable of eating 5-20 percent of their body weight each day. They consume plankton—algae and other microscopic organisms—stripping the food web of the key source of food for small and big fish. Black carp differ in that they consume primarily mollusks, and threaten native mussel and sturgeon populations. These species compete for food with the larval stages of native game fish. Silver carp pose a threat to boaters. The fish leap out of the water when startled by boat engines, often colliding with people and causing injuries.
Listed as injurious wildlife under the Federal Lacey Act, which makes it illegal in the U.S. to import, export, or transport between States without a permit.