Triploid White Amur
(also known as Grass Carp)
SCIENTIFIC NAME: Ctenoparyngodon idella
The triploid (sterile) white amur is an exotic fish species that has been specifically authorized for use in Ohio. Diploid (fertile) white amur remain illegal in Ohio. Pond owners wishing to purchase triploid white amur must do so from a dealer who has a valid White Amur Dealer Permit.
The grass carp, also called white amur, is one of the largest members of the minnow family, and often reaches weights in excess of 25 pounds. White amurs are native to larger East Asian rivers with Pacific drainages, including their namesake, the Amur River on the Chinese-Siberian border. Introductions have expanded their range into over 50 countries and according to some researchers, at least 40 U.S. states.
The grass carp is related to both the common carp and goldfish, but do not have barbels around the mouth as the common carp do. They also have soft dorsal and anal fin rays rather than the spiny rays of common carp or goldfish. Their body shape resembles a large creek chub or common shiner. The color of the grass carp varies from grey to golden brown or bronze on the back, shading to white on the belly.
Sterile or triploid grass carp are the only type of grass carp that are legal to stock in Ohio. Triploid grass carp are created by subjecting the fertilized eggs to high pressures or temperature shock. These procedures result in the retention of an extra chromosome set, rendering the fish incapable of producing viable young. The sterile or triploid offspring are identical to the fertile or diploid parents with the exception of this extra chromosome set.
The stocking of fertile or diploid grass carp is prohibited in Ohio, as well as most other states. This is due to concerns over the potential impact they may have on sensitive aquatic habitats if their reproduction is not controlled.
Stocking rates for grass carp need to be carefully assessed for each body of water. These fish have voracious appetites and overstocking can result in the removal of too much aquatic vegetation. If the grass carp consume too many plants, important habitat is destroyed, and sport fish populations can be adversely effected. Therefore it is recommended that aquatic vegetation be maintained at approximately 20-30% of the ponds surface area. Stocking rates will vary between 5 and 15 fish per acre depending on the amount and type of vegetation, depth and age of the pond, and the type of water supply feeding your pond.