Adult silver carp do not have any natural predators. However, fry are subject to predation from other fish and possibly birds.
Like many other fish, silver carp use their lateral line system to detect motions and vibrations. As filter feeders, however, they do not rely as heavily on their lateral line system as do predatory fish. Silver carp also utilize their senses of sight and smell. Reproduction is often cued by increases in water temperature as well as olfactory cues.
Communication Channels: visual ; chemical
Perception Channels: visual ; tactile ; vibrations ; chemical
Due to their rapid growth rate and worldwide popularity, silver carp are not considered threatened. They are often sold for human consumption and are also used for cleaning waters of algael blooms.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: no special status
Eggs of silver carp reach maturity when they are about 3.2 to 4.7 mm in size. Young enter the larval stage about 68 hours after hatching. During the larval stage, fry are vulnerable and inefficient feeders. After about 5 months, fry have grown to a size of 8 to 12 cm in body length and have become more efficient feeders. Silver carp reach maturity at 4 to 6 years of age, at which point they are capable of reproduction.
The lasting effects of silver carp as invasive spices on local ecosystems remains to be seen.
Silver carp are becoming increasing popular sources of food. They are also commonly used to clear algal blooms. Harvesting of silver carp increased from 1.9 million tons in 1993 to 4.1 million tons in 2003. Because silver carp do not require supplementary feed like other species of farm grown fish, they have become popular worldwide.
Positive Impacts: food ; controls pest population
Silver carp are considered invasive in North America. They were initially introduced into the United States in the 1970’s to control plankton blooms but have subsequently spread into 16 states after escaping from aquaculture centers. Silver carp can adapt to many different environments and can grow very quickly. They can consume 2 to 3 times their body weight in plankton each day. In controlled experiments, silver carp gained 2.7 g/day when fed a large diet. Because of their large size and voracious appetite, silver carp are able to out-compete many other species of fish.
Silver carp are filter feeders, feeding primarily on phytoplankton. Using specialized gill rakers covered with a thick matrix of calcified substances, silver carp are able to filter out the very smallest organisms (ranging in size from 8 to 100 micrometers). However, only a small part of their diet consists of zooplankton and detritus. Silver carp may also eat small arthropods and algea.
Animal Foods: aquatic crustaceans; zooplankton
Plant Foods: algae; phytoplankton
Other Foods: detritus
Foraging Behavior: filter-feeding
Primary Diet: planktivore
Silver carp, Hypophthalmichthys molitrix, are native to eastern Asia and are commonly found in northeastern China and Siberia. They have also been introduced to other areas of the world, and are now considered invasive to North America. Silver carp have been reported in 16 states in the United States and are well established in the Mississippi River Basin.
Biogeographic Regions: nearctic (Introduced ); palearctic (Native )
Silver carp live in freshwater in temperate (6 to 28 °C) to subtropical climates. They are commonly found in impoundments or backwaters of large slow flowing rivers or large lakes. Silver carp are benthopelagic, but they often swim near the surface of the water and are well known for breaching the surface. They can tolerate brackish waters (up to 12 ppt) as well as low dissolved oxygen content (3 mg/l).
Habitat Regions: temperate ; freshwater
Aquatic Biomes: benthic ; lakes and ponds; rivers and streams
With substantial food sources and few natural predators, silver carp can grow quite large and can live many years. Silver carp may live as long as 20 years in the wild, and may be capable of living longer.
Range lifespan
Status: wild: 20 (high) years.
Silver carp are olive green in color on their dorsal side and silver on the ventral side. They have a deep, laterally compressed body and a large head. Their eyes are located near the ventral side, which makes them easily distinguishable from other carp. Both dorsal and anal fins are present, but an adipose fin is lacking. They have 1 to 3 dorsal spines, 1 to 3 anal spines, 6 to 7 soft dorsal rays, and 10 to 14 sot anal rays. The lateral line is approximately 80 to 130 scales in length. They have numerous thin gill rakers (100 or more). Silver carp are also characterized by a smooth ventral keel on the abdomen that runs from the anus to the gill membrane. Silver carp vary considerably in size; most are relatively small (10 to 30 cm), but some can grow as much as 1 m in length and weigh in excess of 60 pounds (27 kg).
Range mass: 27 (high) kg.
Range length: 105 (high) cm.
Average length: 18 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes alike
Silver carp generally reproduce during the spring or summer. Reproduction is primarily cued by increased water temperature. Like other species of carp, silver carp participate in broadcast spawning. During spawning, a female releases eggs and males fertilize them within the water column. A single female can carry as many as 2 million eggs.
Mating System: polygynandrous (promiscuous)
Spawning of silver carp takes place upstream and generally occurs in spring or summer. Optimal water temperatures for spawning range from 22 to 28 °C. Females release eggs in the water column, where they are then fertilized by many males. Fertilized eggs float downstream to floodplain zones where they absorb water and eventually settle to hatch. Silver carp reach sexual maturity at 4 to 6 years of age.
Breeding interval: Silver carp breed once yearly.
Breeding season: Spawning of silver carp occurs during spring or early summer.
Range age at sexual or reproductive maturity (female): 4 to 6 years.
Range age at sexual or reproductive maturity (male): 4 to 6 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); broadcast (group) spawning; oviparous
Silver carp do not demonstrate parental investment in their offspring. After eggs are released into and fertilized in the water column, silver carp leave the area and do not return.
Parental Investment: no parental involvement
The silver carp (Hypophthalmichthys molitrix) is a species of freshwater cyprinid fish, a variety of Asian carp native to China and eastern Siberia, from the Amur River drainage in the north to the Xi Jiang River drainage in the south.[2] Although a threatened species in its natural habitat, it has long been cultivated in China. By weight, more silver carp are produced worldwide in aquaculture than any other species of fish except for the grass carp. Silver carp are usually farmed in polyculture with other Asian carp, or sometimes with catla or other fish species.
The species has also been introduced, or spread by connected waterways, to at least 88 countries around the world. The reason for importation was generally for use in aquaculture, but enhancement of wild fisheries and water quality control have also been intended on occasion.[3] In some of these places, the species is considered invasive.[4][5][6]
The silver carp reaches a typical length of 60–100 cm (24–39 in) with a maximum length of 140 cm (55 in)[7] and weight of 50 kg (110 lb).[2]
The silver carp is a filter feeder, and possesses a specialized feeding apparatus capable of filtering particles as small as 4 µm. The gill rakers are fused into a sponge-like filter, and an epibranchial organ secretes mucus, which assists in trapping small particles. A strong buccal pump forces water through this filter. Silver carp, like all Hypophthalmichthys species, have no stomachs; they are thought to feed more or less constantly, largely on phytoplankton, and also consume zooplankton and detritus. In places where this plankton-feeding species has been introduced, they are thought to compete with native planktivorous fishes, which in North America include paddlefish (Polyodon spathula), bigmouth buffalo (Ictiobus cyprinellus), gizzard shad (Dorosoma cepedianum), and young fish of almost all species.[8][9]
Because they feed on plankton, they are sometimes successfully used for controlling water quality, especially in the control of noxious blue-green algae (cyanobacteria). Certain species of blue-green algae, notably the often toxic Microcystis, can pass through the gut of silver carp unharmed, picking up nutrients in the process. Thus, in some cases, blue-green algae blooms have been exacerbated by silver carp, and Microcystis has also been shown to produce more toxins in the presence of silver carp. These carp, which have natural defenses to their toxins, sometimes can contain enough algal toxins in their systems to become hazardous to eat.[8]
The silver carp in its natural range migrate upstreams for spawning; eggs and larvae then drift downstream, and young fish hatch in the floodplain zone. Larvae and small juveniles feed on zooplankton, switching to phytoplankton once a certain size is reached. The species is somewhat sensitive to low oxygen conditions.
The species is currently classified as near threatened in it original range, as its habitat and reproductive behavior are impacted by construction of dams, pollution, and overfishing. Population declines appear to have been particularly significant in the Chinese parts of its range.[1]
Silver carp are filter feeders, thus are difficult to catch on typical hook-and-line gear. Special methods have been developed for these fish, the most important being the "suspension method", usually consisting of a large dough ball that disintegrates slowly, surrounded by a nest of tiny hooks embedded in the bait.[8] The entire apparatus is suspended below a large bobber. The fish feed on the small particles released from the dough ball and bump against the dough ball, with the intention of breaking off more small particles that can be filtered from the water, eventually becoming hooked on the tiny hooks.
In some areas, using "snagging gear", in which large weighted treble hooks are jerked through the water, is legal to snag the fish. In the United States, silver carp are also popular targets for bowfishing; they are shot both in the water and in the air. In the latter case, powerboats are used to scare the fish and entice them to jump out of the water, and the fish are shot when they are airborne.
Two other species are in the genus Hypophthalmichthys, the bighead carp (H. nobilis) and the largescale silver carp (H. harmandi). The genus name Aristichthys has also sometimes been used for bighead carp, but is deprecated.[10] The bighead carp differs from the silver carp in its behavior (it does not leap from the water when startled) and also in its diet. Bighead carp are also filter feeders, but they filter larger particles than silver carp, and in general consume a greater proportion of zooplankton in their diets than silver carp, which consume more phytoplankton. In at least some parts of the United States, bighead and silver carp hybridize in the wild and produce fertile offspring.
The largescale silver carp is closely related to the silver carp, but its native range is to the south of that of the silver carp, mostly within Vietnam. Unlike bighead and silver carp, largescale silver carp have not been widely introduced around the world for use in aquaculture, although at least one introduction was made to some waters of the Soviet Union, where they hybridized with the introduced silver carp.
Silver carp were imported to North America in the 1970s to control algal growth in aquaculture and municipal wastewater treatment facilities, but escaped from captivity soon after their importation,[4] and are now considered a highly invasive species.[11]
Silver carp, with the closely related bighead carp, often reach extremely high population densities, and are known to have undesirable effects on the local environments and native species, including the bigmouth buffalo.[6][12] They have spread into the Mississippi, Illinois, Ohio, Missouri, Tennessee, Wabash Rivers, and many of their tributaries in the United States, and are abundant in the Mississippi catchment from Louisiana to South Dakota and Illinois. Dams seem to have slowed their advance up the Mississippi River, and until late November 2008, silver carp had not been captured north of central Iowa on the Mississippi.[13] Dams that do not have navigation locks are complete barriers to natural upstream movement of silver carp, unless fishermen unintentionally assist this movement by the use of silver carp as bait.[4][14]
In 2020, Alabama Department of Conservation and Natural Resources found silver carp in Alabama's Pickwick and Wheeler reservoirs on the Tennessee River, but the species has not expanded its range in Alabama’s waterways.[14]
The Tennessee Valley Authority (TVA) has considered several methods to control the spread of Asian carp, including fish barriers at 10 locks controlled by the TVA. One is a bioacoustics fish fence, which uses a combination of sound, light and air bubbles. These barriers are installed at Barkley Lock and Dam in Kentucky, and are currently being studied for their effectiveness in deterring Asian carp. Other types of barriers used for Asian carp include carbon dioxide and electricity. The TVA has conducted environmental impact studies to minimize the impact of the barriers on native species. The TVA has also considered adjusting flow rates during Asian carp spawning periods, which are usually during high-water events, as Asian carp eggs are only semibuoyant and will sink to the bottom and die with low river flow.[14]
The silver carp is sometimes called the "flying" carp for its tendency to leap from the water when startled; it can leap up to 10 ft (3.0 m) into the air.[15] Boaters traveling in uncovered high-speed watercraft have been reported to be injured by running into airborne fish while at speed. A leaping silver carp broke the jaw of a teenager being pulled on an inner tube,[15] and water skiing in areas where silver carp are present is extremely dangerous.[16] Peculiarly, the extreme jumping behavior appears to be unique to silver carp of North America; those in their native Asian range and introduced to other parts of the world are much less prone to jumping. Although theories have been proposed (for example, the high densities the species reaches in parts of North America, or that the introduced North American population may have been based on a small number of particularly "jumpy" individuals), the reason for these geographic differences is not known for certain.[17][18]
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Silver carp caught in Michigan 
Juvenile silver carp The silver carp (Hypophthalmichthys molitrix) is a species of freshwater cyprinid fish, a variety of Asian carp native to China and eastern Siberia, from the Amur River drainage in the north to the Xi Jiang River drainage in the south. Although a threatened species in its natural habitat, it has long been cultivated in China. By weight, more silver carp are produced worldwide in aquaculture than any other species of fish except for the grass carp. Silver carp are usually farmed in polyculture with other Asian carp, or sometimes with catla or other fish species.
The species has also been introduced, or spread by connected waterways, to at least 88 countries around the world. The reason for importation was generally for use in aquaculture, but enhancement of wild fisheries and water quality control have also been intended on occasion. In some of these places, the species is considered invasive.
The silver carp reaches a typical length of 60–100 cm (24–39 in) with a maximum length of 140 cm (55 in) and weight of 50 kg (110 lb).
