Burr et al. (1996) state that, "The potential impact of Hypophthalmichthys molitrix and H. nobilis is not adequately known. Markets for these carp apparently have not become well established. Confusion over the correct identity of these species and the legality of taking this fish in commercial harvests has resulted in its consideration as a nuisance by some fishermen we have interviewed. It is believed these species negatively interact with certain natives but further research before conclusions are drawn."
USGS-NAS (2005) reports that, "Because bighead carp are planktivorous and attain a large size, Laird and Page (1996) suggested these carp have the potential to deplete zooplankton populations. A decline in the availability of plankton can lead to reductions in populations of native species that rely on plankton for food, including all larval fishes, some adult fishes, and native mussels." H. nobilis is also a carrier of several different fish diseases that can be spread through its escape and introduction (FIGIS, 2005).
Location Specific Impacts:
Lake Donghu (China)
Reduction in native biodiversity: In Asia, one of the worst documented negative effects on fish biodiversity has resulted from within country translocations, for example, in Donghu Lake, Wuhan, China when the introduction of grass carp resulted in the decimation of submerged macrophytes and the consequent ecological changes brought about an upsurge of Hypophthalmichthys spp. but also the disappearance of most of the 60 fish species native to the lake (Chen, 1989) (Nguyen and Nakorn, 2004).