From the Amur River of Eastern Russia, grass carp looks like a huge minnow. They are silver olive with white in color. These fish have a laterally compressed body. They grow quickly their first two years, about two inches per month. As a result, they quickly reach 20 pounds or more. Maturity weight is about 40 pounds with a four-foot length. However, specimens to 100 pounds have been reported.
This non-indigenous fish species, also known as Amur Carp or silver orfe – were brought to the USA for aquaculture and for phytoplankton control because of their dietary preference for algae blooms and fast eradication of nuisance aquatic vegetation. They can consume 40-300% of their body mass per day of plant material, depending on their size, feeding by pulling vegetation through their mouth to their “comb-like throat-teeth.” Eating this way means that the pond is not made muddy by pulling plants out the soil by the roots. They have also been reported to also act as janitors, eating waste organic particles, insects, and other invertebrates.
While initially imported because of their benefits, they are now listed as an invasive species with the USDA. Grass carp provide a long-lasting, effective solution for controlling unwanted pond vegetation, but conservative stocking and patience is the best strategy.