Grass Carp - Use As Weed Control

Use As Weed Control

The species was introduced in the Netherlands in 1973 for overabundant aquatic weed control. The release into national waters is controlled and regulated by the Dutch Ministry of Agriculture, Nature and Food Quality. Because grass carp mainly reproduce in water of 25 °C (77 °F), which is much higher than the water temperature reaches during the mating season in the Netherlands, it is necessary to maintain grass carp populations by artificial means, which is done by the person responsible for the water body in which the fish were introduced. Where grass carp populations are maintained through stocking as a biocontrol for noxious weeds, they should be returned to the water alive and unharmed.

When used for weed control, often the fish introduced to the pond or stream are sterile, triploid fish. The process for producing triploid fish involves shocking eggs with a rapid change in temperature or pressure. This process is not usually 100% effective, therefore, in the United States, the young are usually tested for triploidy before being sold. Bait often consists of vegetables or fruits that are native to the area.