Carp were origianlly brought over from Europe where they were a prized food fish. These fish are found in almost all water bodies in the state. They are extremely tolerant of poor water quality, which has contributed to its spread. Carp feeding activity can cause poor water quality, due to their habit of rooting the bottom and stirring up sediment in search of food. The aggravation of bottom sediments reduces visiblility for predatory fish and limits light penetration for plant growth.
Common carp are prolific spawners and can quickly overrun a body of water.
With their large size, they can also dominate the total fish biomass of a body of water, leaving little room for more popular game species. It was brought into the United States for nuisence aquatic vegetation control. In controlled situations the grass carp has proved a valuable tool for managers to use for weed control. Grass carp need long river stretches for spawning and incubation of young. To the best of our knowledge grass carp have not been found naturally spawning in Iowa's portion of the Mississippi.