Grass Carp: Interesting and Unusual Gamefish

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Grass Carp: Interesting and Unusual Gamefish

Grass carp are a conditional species in Florida and can only be possessed by permit. Any grass carp caught must be released immediately–but they’re interesting and unusual gamefish for catch and release.

Size: The largest triploid grass carp documented in Florida was 15 years old, 56″ long and weighed 75 lbs. Because this is a conditional species in Florida it is not eligible for State Records or Big Catch.

Identification and similar species: The grass carp is one of the largest members of the minnow family. The back of the grass carp is silvery to dark grey, and the sides of the body are lighter with a slightly golden sheen. The belly is silvery white. Fins are generally greenish grey. The fish has relatively large scales. The body shape is oblong with a round belly and broad head. Teeth have been replaced by specialized structures called pharyngeal teeth (see photo) located in the back of the throat. These are used for tearing and grinding plant matter.

By contrast, common carp have a laterally compressed, robust body (deep bodied from the back of the fish to the belly) and are easily distinguished by the presence of barbels (whiskers) located at the corners of the mouth.

Angling qualities: Sometimes taken by anglers, especially those fishing for catfish or tilapia, but they must be released immediately and unharmed since those found in Florida were stocked deliberately for aquatic plant control purposes. As the name implies grass carp consume higher aquatic plants and submerged grasses (rooted macrophytes as opposed to algaes); they will also eat detritus, insects and other invertebrates when necessary. Because of their feeding behavior, they are used in this country under special restricted circumstances (see the FWC Grass Carp Permit page for details) to help manage aquatic plant problems. Many aquatic plants that pose problems in Florida are exotic and have few natural insect or disease controls, consequently they frequently create problems with access, navigation, flood control, irrigation and aesthetics. Since chemical herbicides and mechanical removal are costly alternatives, biocontrol agents, such as triploid grass carp can provide a beneficial tool. Triploid grass carp have three sets of chromosomes, instead of the normal two, which renders them functionally sterile. Triploids are produced artificially, by using hormones, stripping the eggs and mixing them with milt, then subjecting the fertilized egg to hydrostatic pressure, and finally suspending the fertilized eggs in well-aerated containers until they hatch. The resultant fish must be individually tested using a Coulter Counter, in a certification process developed by FWC biologists prior to being permitted for use. The FWC helps protect aquatic habitats by restricting the use of grass carp via permits to only these sterile fish and limiting the number allowed.

Where to find them: The grass carp is native to large coastal rivers in Siberia and China. In Florida, sterile Triploid Grass Carp are stocked throughout the state by permit for biological vegetation control.