TRIPLOID GRASS CARP 8-10" (Ctenopharyngodon idella) are commonly stocked in lakes and ponds to control excessive aquatic vegetation. Techniques to create sterile fish allow pond owners to effectively manage vegetation without risking the environmental harm that can come from an uncontrolled, breeding population of grass carp. 

HISTORY: Grass carp are a member of the minnow family. Though native to river systems of Asia, they have been introduced worldwide as a food fish and for aquatic vegetation management. They feed on vegetation in shallow waters and are highly tolerant of a large temperature range. These fish were imported to the United States in 1963 to aquaculture facilities in Alabama and Arkansas as a biological control for aquatic plants. Concerns over their impact on native ecosystems led to the development of non-reproductive fish. 

Sterile fish are developed by subjecting the eggs to heat or pressure. The stress causes the cells to retain a third set of chromosomes, instead of the normal two sets. This extra set of chromosomes renders these fish sterile. The U.S. Fish and Wildlife Service tests fish from each lot of triploid fish to certify them as triploid. 

ALIAS: Sterile grass carp, triploid white amur

IDENTIFICATION: Triploid grass carp are an elongated, torpedo-shaped fish with a terminal mouth and no barbels. They are dark olive to brownish yellow in color and have large scales along the length of their body.

DIET: Aquatic weeds such as curly-leaf pondweed, coontail and duckweed.

SPAWNING: Triploid grass carp are certified sterile by the U.S. Fish and Wildlife Service and will not reproduce.

TRIVIA: Ohio legalized the sale of triploid grass carp in 1988. 

  8+ fish per acre stocking rate is recommended.