Datasheet

Enhanced

25 September 2019

Hypophthalmichthys molitrix (silver carp)

Authors: Vicki Bonham, Tagried KurwieAuthors Info & Affiliations

Publication: CABI Compendium

79036

https://doi.org/10.1079/cabicompendium.79036

Datasheet Types: Cultured aquatic species, Invasive species, Host animal

Abstract

This datasheet on Hypophthalmichthys molitrix covers Identity, Overview, Associated Diseases, Pests or Pathogens, Distribution, Dispersal, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Prevention/Control, Management, Genetics and Breeding, Economics, Further Information.

Identity

Preferred Scientific Name: Hypophthalmichthys molitrix (Valenciennes, 1844)
Preferred Common Name: silver carp
Other Scientific Names: Abramocephalus microlepis Steindachner, 1869; Cephalus mantschuricus Basilewsky, 1855; Hypophthalamichthys molitrix Berg, 1940; Hypophthalmichthys dabry Guichenot, 1871; Hypophthalmichthys dybowskii Herzenstein, 1888; Hypophthalmichthys microlepis (Steindachner, 1869); Hypothalmichthys molitrix (Valenciennes, 1844); Hypothamicthys molitrix (Valenciennes, 1844); Leuciscus hypophthalmus Richardson, 1945; Leuciscus molitrix Valenciennes, 1844; Onychodon mantschuricus Basilewsky, 1872
International Common Names: English
carp
carp, silver
Chinese schemer; Spanish
carpa plateada; French
amour argenté
carpe argentée
carpe asiatique
carpe chinoise; Russian
belyi tolstolob
belyi tolstolobik
tolpyga
tolstolobik
Local Common Names: Albania
ballgjeri i bardhe; Bulgaria
byal tolstolob; China/Hong Kong
bin ue
cho ue
lin ue; Czech Republic
tolstolobik bílý
tolstolobik obecný; Denmark
sølvkarpe; Finland
hopeapaksuotsa; Germany
Silberkarpfen
Tolstolob; Greece
asimokyprinos; Hungary
fehér busa; India
belli-gende; Iran
fytofag
kopur noqreai
phytophague; Israel
kap perak
kasaf; Italy
carpa argentata; Japan
hakuren; Malaysia
kap perak
tongsan putih; Netherlands
zilverkarper; Norway
sølvkarpe; Philippines
babangan; Poland
tolpyga biala
toplyga biala; Portugal
carpa prateada
carpa-prateada; Romania
crap argintiu
crap-chinezesc-argintiu
sânger; Slovakia
tolstolob biely; South Africa
silwerkarp; Sweden
silverkarp; Thailand
pla leng hea
pla leng heu
pla lin
pla pae long
pla pea long
pla pin hea
pla pin heu; Ukraine
belyi tolstolobik
tolstolobik
tovstolob zvychajnyi

Pictures

Adults
Hypophthalmichthys molitrix (silver carp); Adults leaping from the water. USA. November 2008.
©Asian Carp Regional Coordinating Committee/via flickr - CC BY 2.0

Spawning female
Silver carp ready for spawning.
©Mahurangi Technical Institute/New Zealand

Adult
Hypophthalmichthys molitrix (silver carp); Adult. USA. May 2012.
©Asian Carp Regional Coordinating Committee/via flickr - CC BY 2.0

Spawning female
A typical silver carp ready to spawn. Notice the bruises on the body.
©Mahurangi Technical Institute/New Zealand

Species comparison
Hypophthalmichthys molitrix (silver carp); adult silver carp (a) compared with bighead carp (Aristichthys nobilis) (b). Also to note, bighead carp do not leap from the water when disturbed by boats, etc.
©Asian Carp Regional Coordinating Committee/via flickr - CC BY 2.0

Algae bloom
Using silver carp to control algae bloom in Hawkes Bay, New Zealand.
©Andy D. Carruthers/NIWA, New Zealand

Fishing
Silver carp, Hypophthalmichthys molitrix, jumping to escape from a fishing net. Israel.
©Ana Milstein

Overview

Hypophthalmichthys molitrix is a freshwater fish belonging to the order Cypriniformes and the family Cyprinidae (carp). It feeds by filter-feeding of plankton. It is native to China and the adjacent part of Russia. It is much cultivated for food in China, and to a significant extent in other countries. Worldwide aquaculture production of the species has increased from just over 400,000 tonnes in 1980 to over 4.8 million tonnes in 2019, making it one of the major species produced in world aquaculture, third only to grass carp (Ctenopharyngodon idella) and the shrimp Penaeus vannamei; it accounted for 10% of world production in 2016. It is often grown in polyculture with other cyprinids, to maximise the efficiency of use of food resources. It is often used, both in aquaculture and in other contexts, to control excessive growth of plankton, although its effectiveness for this is not universally accepted. It has been introduced to many countries around the world for aquaculture and plankton control; it is considered invasive in North America.

Summary of Invasiveness

Hypophthalmichthys molitrix is a freshwater fish belonging to the order Cypriniformes and the family Cyprinidae (carp). It is native to China and the adjacent part of Russia; it is much cultivated for food in China, and to a significant extent in other countries – it is one of the major species produced in world aquaculture. It has been introduced to many countries around the world for aquaculture and plankton control. It is considered invasive in North America, where it is present and established in many states of the Mississippi basin and there is concern about its potential spread to the Great Lakes. It appears to have an adverse effect on native fish through its high consumption of plankton, and it can injure people, and spread zoonotic diseases, as a result of its habit of leaping out of the water when disturbed.

Taxonomic Tree

Description

Hypophthalmichthys molitrix is a large, rather heavily built cyprinid, laterally compressed when small but becoming increasingly robust and thick-bodied with growth. It is covered with small cycloid scales of a uniform silver coloration. The lateral line curves downwards very markedly in the abdominal region, more or less following the profile of the belly. There are between 95 and 103 scales (some references quote 120) in the lateral line.

There is a single, smallish, flag-like dorsal fin (nine rays); the dorsal fin origin is behind the pelvic fin insertion. The anal fin is rather longer and shallower (15-17 rays). The moderately long and flattened caudal peduncle supports a deeply forked, strong caudal fin. The pelvic fins (seven or eight rays) are smallish, triangular and abdominal. The pectoral fins (15-18 rays) are rather larger, reaching back to the insertion of the pelvic fins. Small specimens do not have spines on their fins, whereas large specimens have a hard, stiff spine with fine serrations on the posterior margin, at the front end of the pectoral, and moderately strong spines on the dorsal and anal fins (the New Zealand introduced variety seems to lack the spines).

Keels extend from isthmus to anus. The eyes are low on the head with their lower margin below the mouth corner level. The mouth is terminal, with no barbels, and is relatively large, upturned and toothless.

Sexes in Hypophthalmichthys molitrix are morphologically different, but sexual dimorphism is not very clear even during the breeding season and not constant for all age classes (Woynarovich and Horvath, 1980; Jhingran and Pullin, 1988). The variations include roughness of the inner surface of the pectoral fins of the male while that of the female is soft to the touch (T Kurwie, Mahurangi Technical Institute, New Zealand, personal observation, 2004). The shape of the pectoral fin also shows some morphological differences -- the pectoral fin of the male is relatively long and prominent with a well-developed thick outermost ray, whereas that of the female is relatively small and weak with the outermost ray not very thick (Jhingran and Pullin, 1988). The variation near spawning time is more prominent as the female shows a conspicuous bulge which extends past the pelvis up to the genital aperture; this bulge could be due to fat deposits around the gut. The abdomen is soft to the touch. The male does not generally show a conspicuous bulge and is not very soft to the touch. During the breeding season, milt is released from the genital aperture of the male when slight pressure is applied to the belly.

Kamilov (1985) found that the first ray of the pectoral fin, the vertebrae and the pterygiophore of the first ray of the dorsal fin were suitable for ageing this species, whereas the operculum and the otoliths were not suitable. However, Johal et al. (2000) reported that the postcleithrum was more accurate for measuring age.

Kamilov and Salikhov (1996) reported that specimens of up to 1260 mm had been fished from the Syr Darya River in Central Asia. The maximum recorded weight of the species is 50 kg (Billard, 1997).

Pathogens Carried

Distribution

Hypophthalmichthys molitrix naturally occurs in the temperate fresh waters of China. It inhabits the river systems of the Yangtze, West River, Pearl River, Kwangsi and Kwangtung in South and Central China, and also the Amur Basin in the east of Russia (Jhingran and Pullin, 1988).

It has been widely introduced around the world, in many cases for aquaculture and in some cases for plankton control. In the USA, where it was introduced in the 1970s, it has spread rapidly and is regarded as an invasive species.

Distribution Map

Distribution Table

History of Introduction and Spread

Hypophthalmichthys molitrix has been introduced to many countries around the world for aquaculture or phytoplankton control, although it is only in North America that it is of concern as an invasive species.

The species was first introduced in 1973 in Arkansas into aquaculture ponds to control plankton. By the end of the 1970s, many private and federal aquaculture facilities and sewage lagoons in the USA had been stocked with H. molitrix. It is now present in many states in the Mississippi basin, with a few records from other states (US Geological Survey, 2022); there has been uncertainty about the extent to which breeding takes place (US Geological Survey, 2022), but the species is reported as having 'increased exponentially in the Mississippi River Basin' (Chapman, 2010), as being 'well established' there (Invasive Carp Regional Coordinating Committee, 2022), and as having been reproducing in the Upper Mississippi system by 2000 (Koel et al, 2000).

In their summary of risk of spread in the contiguous US, the US Fish and Wildlife Service note that Hypophthalmichthys molitrix has a high history of invasiveness since its introduction, having escaped captivity and spread rapidly with documented negative impacts (e.g. alterations to the zooplankton community, lowered body condition of native planktivores). They also note that H. molitrix are a significant threat to humans, as they may transfer zoonotic pathogens and/or cause bodily injury and property damage by jumping out of the water (US Fish and Wildlife Service, 2019).

Hypophthalmichthys molitrix has now reached the threshold of the Laurentian Great Lakes, where there is concern that it will impact food chains and fisheries (Chapman, 2010). Stepien et al. (2019) tested environmental (e)DNA water samples from the Great Lakes region (along the Lake Erie, Lake St. Clair and Wabash River watersheds) and found silver carp eDNA in three of the Lake Erie samples and one in the Wabash River watershed sample. These findings provide information for both understanding and tracing introductions, as well as vectors and spread pathways, for H. molitrix (and also related species).

Introductions

Introduced to	Introduced from	Year	Reasons	Introduced by	Established in wild through		References	Notes
Introduced to	Introduced from	Year	Reasons	Introduced by	Natural reproduction	Continuous restocking	References	Notes
Afghanistan			Aquaculture (pathway cause) Biological control (pathway cause) Fisheries (pathway cause)	Unknown	No	Yes	FAO (2019a)
Albania			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Algeria	Hungary	1991	Fisheries (pathway cause)	Government	No	Yes	FAO (2019a)
Armenia			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Austria			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Bangladesh		1969		Unknown	No	No	FishBase (2005)
Belgium	Yugoslavia (former)	1975	Biological control (pathway cause)	Private sector	No	Yes	FAO (2019a)
Bhutan		1982-1983		Unknown	No	No	FishBase (2005)
Brazil		1983	Aquaculture (pathway cause)	Government	No	No	FAO (2019a)
Bulgaria			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Cambodia			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Colombia	Taiwan	1988	Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Costa Rica	Taiwan	1976	Aquaculture (pathway cause)	Unknown	No	Yes	FAO (2019a)
Cyprus	Israel	1976	Hunting, angling, sport or racing (pathway cause)	Unknown	Yes	No	FAO (2019a)
Cuba	Former USSR	1978	Aquaculture (pathway cause)	Unknown	No	Yes	FAO (2019a)
Czechoslovakia (former)		1953	Aquaculture (pathway cause)	Unknown	Yes	No	FAO (2019a)
Denmark			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Dominican Republic	Taiwan	1981	Aquaculture (pathway cause)	Government	No	No	FAO (2019a)
France	Hungary	1975	Biological control (pathway cause)	Unknown	Yes	No	FAO (2019a)
Egypt	Japan	1962	Research (pathway cause)	Unknown	No	No	FAO (2019a)
Estonia	Former USSR	1980s	Biological control (pathway cause)	Government	No	No	FAO (2019a)
Ethiopia	Japan	1975	Aquaculture (pathway cause)	Unknown	No	Yes	FAO (2019a)
Fiji	Malaysia	1969	Research (pathway cause)	Unknown	No	Yes	FAO (2019a)
Germany	Hungary	1970	Aquaculture (pathway cause)	Unknown	No	Yes	FAO (2019a)
Greece	Poland	1980	Fisheries (pathway cause)	Unknown	Yes	No	FAO (2019a)
Guam	Taiwan	1974	Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Haiti	Panama				No	No	FAO (2019a)
Honduras	Taiwan	1976	Aquaculture (pathway cause)	Unknown	No	Yes	FAO (2019a)
Hungary		1968	Biological control (pathway cause) Aquaculture (pathway cause)	Government	Yes	Yes	FAO (2019a)
India		1959		Unknown	No	No	FishBase (2005)
Indonesia		1964		Unknown	No	No	FishBase (2005)
Iran		1992	Biological control (pathway cause) Aquaculture (pathway cause) Fisheries (pathway cause)	Government	Yes	No	FAO (2019a)
Iraq		1966-1969		Unknown	No	No	FishBase (2005)
Israel		1966		Unknown	No	No	FishBase (2005)
Italy			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Jamaica			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Japan		1878-1940		Unknown	No	No	FishBase (2005)
Jordan		1966		Unknown	No	No	FishBase (2005)
Kazakhstan		1958-1959		Unknown	No	No	FishBase (2005)
Korea, Republic of	Japan	1963	Aquaculture (pathway cause) Research (pathway cause)	Government	No	No	FAO (2019a)
Laos					No	No	FAO (2019a)
Latvia					Yes	No	FAO (2019a)
Lebanon			Aquaculture (pathway cause) Biological control (pathway cause)		No	Yes	FAO (2019a)
Lesotho	South Africa	1988	Aquaculture (pathway cause)		No	No	FAO (2019a)
Madagascar	Korea, DPR	1982	Research (pathway cause)		No	No	FAO (2019a)
Malawi	Israel	1970	Aquaculture (pathway cause)	International organisation	No	No	FAO (2019a)
Malaysia		1888-1889		Unknown	No	No	FishBase (2005)
Mauritius	India	1976		Unknown	No	No	FAO (2019a)
Mexico	China	1965	Aquaculture (pathway cause)	Government	No	Yes	FAO (2019a)
Moldova			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Morocco	Bulgaria	1980	Biological control (pathway cause)	Unknown	Yes	No	FAO (2019a)
Mozambique	Cuba	1991	Aquaculture (pathway cause)	International organisation	No	No	FAO (2019a)
Myanmar	China		Aquaculture (pathway cause)	Government	No	No	FAO (2019a)
Nepal		1965		Unknown	No	No	FishBase (2005)
Netherlands	Hungary	1966		Unknown	No	No	FAO (2019a))
New Zealand	Hong Kong	1969	Biological control (pathway cause) Research (pathway cause)	Unknown	No	Yes	FAO (2019a)
Nigeria		1984	Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Pakistan		1982-1983		Unknown	No	No	FishBase (2005)
Panama	Taiwan	1978	Aquaculture (pathway cause)	Unknown	No	Yes	FAO (2019a)
Papua New Guinea				Unknown	No	No	FAO (2019a)
Peru	Panama	1979	Aquaculture (pathway cause)	Unknown	No	Yes	FAO (2019a)
Philippines		1964		Unknown	No	No	FishBase (2005)
Poland	Former USSR	1964	Aquaculture (pathway cause) Biological control (pathway cause)	Government	No	Yes	FAO (2019a)
Puerto Rico	USA	1972		Unknown	No	No	FAO (2019a)
Romania	China	1960	Aquaculture (pathway cause) Biological control (pathway cause)	Government	Yes	Yes	FAO (2019a)
Russian Federation		1953	Aquaculture (pathway cause)	Unknown	Yes	No	FAO (2019a)
Rwanda	Korea, Republic of	1979	Aquaculture (pathway cause)	Unknown	No	Yes	FAO (2019a)
Saudi Arabia			Aquaculture (pathway cause) Biological control (pathway cause)	Unknown	No	Yes	FAO (2019a)
Sri Lanka		1948		Unknown	No	No	FishBase (2005)
Singapore	China	1900s	Aquaculture (pathway cause)	Private sector	No	No	FAO (2019a)
Slovakia					Yes	No	FAO (2019a)
South Africa	Israel	1975	Aquaculture (pathway cause)	Unknown	Yes	No	FAO (2019a)
Sweden			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Switzerland		1970	Biological control (pathway cause)	Government	No	No	FAO (2019a)
Taiwan	China	1981	Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Tanzania	India		Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Thailand	China	1913	Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Tunisia	Hungary	1981	Biological control (pathway cause)	Government	No	No	FAO (2019a)
Turkey			Aquaculture (pathway cause)	Unknown	No	Yes	FAO (2019a)
Turkmenistan	China		Aquaculture (pathway cause)	Unknown	Yes	No	FAO (2019a)
UK			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Ukraine			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
USA		1970s	Aquaculture (pathway cause) Hunting, angling, sport or racing (pathway cause)	Unknown	No	Yes	FishBase (2005)
Uzbekistan			Aquaculture (pathway cause)	Unknown	Yes	No	FAO (2019a)
Vietnam	China	1958	Aquaculture (pathway cause)	Unknown	Yes	Yes	FAO (2019a)
Yugoslavia (former)	Romania	1963	Aquaculture (pathway cause)	Unknown	Yes	No	FAO (2019a)
Zambia			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)
Zimbabwe			Aquaculture (pathway cause)	Unknown	No	No	FAO (2019a)

Risk of Introduction

In North America, there is concern that Hypophthalmichthys molitrix could spread into the Great Lakes. In their summary of risk of spread in the contiguous US, the US Fish and Wildlife Service note that all 48 states have a suitable climate for the species (US Fish and Wildlife Service, 2019).

The authorities in the states and province bordering the Great Lakes consider it likely that if Hypophthalmichthys molitrix reaches the Great Lakes, it will (migrating with and against currents and leaping over barriers) quickly and extensively establish itself there and in connected waters, as have other invasive species such as zebra mussels (Dreissena polymorpha), gobies, the sea lamprey (Petromyzon marinus) and the alewife (Alosa pseudoharengus). The Great Lakes lie within the latitudes of the native range of the species, which has proven to be highly active in cold waters in the US, feeding at temperatures at least as low as 2.5°C.

Anatomy

Dentition

The mouth is toothless. The pharyngeal teeth are in one row (4-4) and are well developed and compressed with a striated grinding surface.

Gills

The gills have a complex of network and profusion of closely set gill rakers, which exceed 650 in number and are longer than the gill filaments (Peirong, 1989). The gill membranes are not connected to the isthmus (Peirong, 1989; McDowall, 1990; FishBase, 2005).

Digestive System

Hypophthalmichthys molitrix, like all cyprinids, have a simple digestive system. The gut is anatomically modified to the feeding habit of filter feeding phytoplankton and zooplankton. The length of the gut of the adult fish is 15 times the body length; the intestine is also reported to be six to ten times the body length. The gut is complexly coiled.

Reproductive System

The ovaries are typical of fish ovaries. One pair of sac-like ovaries is located symmetrically in the body cavity. The walls are formed by connective tissue and smooth muscle. The inner wall of the ovary protrudes and forms the septum (ovum-producing plate) which is responsible for producing the ova. Following sexual maturity the follicular membranes break and the ova drop into the ovarian cavity. At the end of the ovarian cavity, there is a short oviduct that opens to the exterior of the body. The ovarian tissues are supplied with a net of blood vessels and nerves.

Male Hypophthalmichthys molitrix possess typical teleost fish testes. They are paired and tubular, and are situated on the both sides of the air bladder, attached to the coelomic wall. The mature testes are white. The inner part consists of many irregularly arranged ampullae-like structures and the spaces between them are full of connective tissue. The ampullae are composed of many spores (seminal vesicle sacs). Spore sacs are separated by a thin layer of follicular cells. Each spore sac contains synchronously developing germ cells and germ cells in various stages of development can be seen in different spore sacs. At the centre of the ampullae, there is a hollow cavity. After the formation of the sperm cells, the spore sacs dissolve and the sperm enter this cavity. The terminal end of the testis is connected to the short seminal duct with an opening to the exterior of the body (Yu, 1989).

Skeleton

The total number of vertebrae is 36-40.

Habitat List

Category	Sub category	Habitat	Presence	Status
Freshwater

Climate

Climate type	Description	Preferred or tolerated
A - Tropical/Megathermal climate	Average temp. of coolest month > 18°C, > 1500mm precipitation annually	Tolerated
C - Temperate/Mesothermal climate	Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C	Preferred
D - Continental/Microthermal climate	Continental/Microthermal climate (Average temp. of coldest month < 0°C, mean warmest month > 10°C)	Tolerated

Air Temperature

Parameter	Lower limit (°C)	Upper limit (°C)
Absolute minimum temperature	0.5
Mean maximum temperature of hottest month	32	40
Mean minimum temperature of coldest month	>0.5

Water Tolerances

Parameter	Minimum value	Maximum value	Typical value	Status	Life stage
Ammonia [unionised] (mg/l)			0.1	Optimum	Adult
Ammonia [unionised] (mg/l)			13	Harmful	Adult
Ammonium [ionised] (mg/l)			>2	Harmful	Egg
Ammonium [ionised] (mg/l)			>3	Harmful	Adult
Ammonium [ionised] (mg/l)			1.5	Optimum	Egg
Ammonium [ionised] (mg/l)			up to 3	Optimum	Adult
Dissolved oxygen (mg/l)			<2	Harmful	Adult
Dissolved oxygen (mg/l)			<4	Harmful	Broodstock
Dissolved oxygen (mg/l)			<4	Harmful	Larval
Dissolved oxygen (mg/l)			<5	Harmful	Egg
Dissolved oxygen (mg/l)			>4	Optimum	Larval
Dissolved oxygen (mg/l)			>5	Optimum	Egg
Dissolved oxygen (mg/l)			4	Optimum	Adult
Dissolved oxygen (mg/l)	4	5		Optimum	Broodstock
Iron (mg/l)			>0.02	Harmful	Adult
Iron (mg/l)			0.02	Harmful	Egg
Iron (mg/l)			0.02	Harmful	Larval
Iron (mg/l)			below 0.02	Optimum	Egg
Iron (mg/l)			below 0.02	Optimum	Larval
Iron (mg/l)			up to 0.02	Optimum	Adult
Manganese (mg/l)			>0.02	Harmful	Adult
Manganese (mg/l)			0.02	Harmful	Egg
Manganese (mg/l)			0.02	Harmful	Larval
Manganese (mg/l)			below 0.02	Optimum	Egg
Manganese (mg/l)			below 0.02	Optimum	Larval
Manganese (mg/l)			up to 0.02	Optimum	Adult
Nitrate (mg/l)			>15	Harmful	Adult
Nitrate (mg/l)			1	Optimum	Egg
Nitrate (mg/l)			1	Optimum	Larval
Nitrate (mg/l)			10	Harmful	Egg
Nitrate (mg/l)			10	Harmful	Larval
Nitrate (mg/l)			up to 15	Optimum	Adult
Nitrite (mg/l)			<0.5	Optimum	Egg
Nitrite (mg/l)			<0.5	Optimum	Larval
Nitrite (mg/l)			>0.5	Harmful	Adult
Nitrite (mg/l)			>0.5	Harmful	Egg
Nitrite (mg/l)			>0.5	Harmful	Larval
Nitrite (mg/l)			up to 0.5	Optimum	Adult
Salinity (part per thousand)			0	Optimum	Egg
Salinity (part per thousand)			1	Harmful	Egg
Salinity (part per thousand)	0	1		Optimum	Adult
Salinity (part per thousand)	0	1		Optimum	Broodstock
Water pH (pH)	7.5	8.5		Optimum	Adult
Water pH (pH)	7.5	8.5		Optimum	Broodstock
Water temperature (ºC temperature)	22	24		Optimum	Broodstock

Diseases, Disorders and Natural Enemies

Health

Anchor worm disease (Lernaea sp.)

The head of the copepod parasite is hooked a few millimetres inside the fish, and only the body with two egg sacs hangs freely in the water. An ulcer may appear at the site where the parasite is located. This can result in bacterial infection and later may develop secondary fungal infection (Bassleer, 2003).

Bothriocephalus infestation

Bothriocephalus acheiolognathi is a tapeworm that can be found in the intestines of Hypophthalmichthys molitrix.

Gill fluke disease

Fluke infestation occurs most commonly on the gills and skin, and can cause the following: gills swollen and pale, high mucus secretion, spread opercula, restlessness, gathering near water inflow, gasping air, heavy ventilation, dark colour, loss of weight, cessation of feeding, swimming at high speed, jumping out of water, scraping against objects, epithelial outgrowths and tissue swelling on gills, serious epizootics and mortality.

Trichodinosis

This disease is caused by Trichodinella sp. and affects a wide variety of fish. Symptoms include a slime that covers the skin like fog, and fins that are clamped and denuded of tissue.

Myxobolus infection

Infestation occurs most commonly in the gills.

Whirling disease

This generally invades the host in the form of cytocysts of Myxobolus lieni, which attacks the central nervous system and sensory organs of Hypophthalmichthys molitrix and H. nobilis, causing whirling disease (Shaoqi, 1989).

Enteric redmouth

This disease, caused by the bacterium Yersinia ruckeri, mainly affects salmonids, but it has also been recorded in wild and cultured Hypophthalmichthys molitrix (Horne and Barnes, 1999).

Vertical scale disease

This is caused by Pseudomonas punctata [Aeromonas punctata?]. The skin of the infected fish appears rough and scales, especially on the posterior part of the body, are stretched out causing a resemblance to a pinecone (thus it is called pinecone disease). The scale capsule contains a semi opaque or sanguineous liquid that makes the scale vertical. When slight pressure is applied, the liquid exudes and the scale falls off. Other symptoms include congestion on the fin base, mild bleeding and inflammation on the skin, exophthalmia (protruding eyeballs) and abdominal distension. As the disease develops fish swim slowly and show dyspnoea, and the abdomen turns upward. The fish die 2-3 days later (Shaoqi, 1989).

Spring viraemia of carp

Spring viraemia of carp (SVC) is a systemic, acute and highly contagious disease caused by Rhabdovirus carpio (Spring viremia of carp virus), which is a typical bullet-shaped virion. The gill is the most common portal of entry. Infected cells develop cytoplasmic inclusion bodies and mature virions are released by budding from the plasma membrane. SVC is transmitted horizontally and by blood sucking parasites such as the fish louse Argulus foliaceus and the leech Piscicola geometra (Petty et al., 2002, 2019).

Predation

Several genera of aquatic insects are recorded as predators of larvae or fry of Hypophthalmichthys molitrix (Jhingran and Pullin, 1988).

In a study of prey selectivity, Wolf and Phelps (2017) found that white bass (Morone chrysops) and largemouth bass (Micropterus salmoides), common predator fish from the Mississippi River system in the USA, showed significant avoidance of Hypophthalmichthys molitrix compared to native prey fish. Trends observed in the field were supported by laboratory experiments.

List of Diseases and Disorders

Natural enemies

Natural enemy	Type	Life stages	References
Belostomatidae	Predator	Larval Fry	Jhingran and Pullin (1988)
Coenagrionidae	Predator	Larval Fry	Jhingran and Pullin (1988)
Corixidae	Predator	Larval Fry	Jhingran and Pullin (1988)
Dytiscidae (predacious diving beetles)	Predator	Larval Fry	Jhingran and Pullin (1988)
Hydrophilidae (water scavenger beetles)	Predator	Larval Fry	Jhingran and Pullin (1988)
Nepidae	Predator	Larval Fry	Jhingran and Pullin (1988)
Notonectidae	Predator	Larval Fry	Jhingran and Pullin (1988)

Impact Summary

Category	Impact
Biodiversity (generally)	Negative
Environment (generally)	Positive and negative
Fisheries / aquaculture	Positive
Human health	Negative
Native fauna	Negative
Native flora	Negative

Impact: Economic

The risk of human injuries from leaping Hypophthalmichthys molitrix may, by impacting recreational activities, have adverse economic impacts as well. Asian carp in general may have significant impacts on commercial fisheries, and measures to control them can be very expensive (e.g. 10 million dollars to install an electrical barrier to keep them out of the North American Great Lakes) (Oregon State University, 2010).

Impact: Environmental

In North America, Hypophthalmichthys molitrix is considered to be an invasive species in a number of states of the USA. Its presence in the Mississippi River drainage, which includes the Missouri and Ohio rivers and their tributaries, is causing concern about widespread and fast growth compared to the native fish. It is thought that the species has the potential to damage the ecosystem by adversely affecting the food chain of native fish, competing with them for food and space. This concern is based on the fact that H. molitrix and bighead carp [Hypophthalmichthys nobilis or Aristichthys nobilis] exceed 90% of the commercial catch in Europe and Asia where they have been introduced. As a filter feeder, it is thought that H. molitrix competes with US native species such as paddlefish (Polyodon spathula), bigmouth buffalo (Ictiobus cyprinellus), freshwater clams and larval fish (Chapman, 2004, 2010).

Although many note the negative effects on Asian carp on native fish, few actual studies exist. Phelps et al. (2017) set out to evaluate the interaction between Asian carp and native fish and found, using data from a 20-year long-term monitoring program, that in the Mississippi River, relative abundance of Hypophthalmichthys molitrix had increased while relative abundance and condition of native planktivores had declined.

As filter feeders, Hypophthalmichthys molitrix (and H. nobilis) have the potential to deplete plankton populations, especially when they are at high densities; indeed they have often been introduced for this purpose. Loss of plankton will affect other planktivorous organisms, such as juvenile fish and mussels. However, the impact of carp on plankton is highly variable, due to differences in stocking densities and species of plankton. Some noxious blue-green algae are controlled by these carp, but others are not and can even be exacerbated (because they pass through the gut of the fish unharmed, and pick up nutrients on the way). Also, consumption of zooplankton and larger and colonial phytoplankton leaves an open niche that is often filled by nanophytoplankton. Research has been conducted exclusively in lakes, so the effects in river ecosystems are unknown (Oregon State University, 2010).

Impact: Social

Hypophthalmichthys molitrix is not welcomed in many states of the USA as it poses considerable hazards to fishermen and water skiers who frequently complain that, when startled, the fish jump up to 6 feet or more out of the water, causing damage by landing in boats and causing human injuries, some of them serious (Chapman, 2004, 2010; US Fish and Wildlife Service, 2019). There is also a risk of transfer of zoonotic pathogens to people (US Fish and Wildlife Service, 2019). It has been reported to be an effective carrier of Salmonella typhimurium (ISSG, 2022).

The species can have significant impacts on sport and commercial fisheries and endanger recreational boaters and water skiers.

Risk and Impact Factors

Invasiveness

Proved invasive outside its native range

Benefits from human association (i.e. it is a human commensal)

Has high reproductive potential

Impact outcomes

Negatively impacts human health

Negatively impacts tourism

Reduced amenity values

Reduced native biodiversity

Threat to/ loss of native species

Impact mechanisms

Competition - monopolizing resources

Filtration

Likelihood of entry/control

Highly likely to be transported internationally deliberately

Uses

Hypophthalmichthys molitrix has been introduced to many countries all over the world for two reasons: aquaculture as a source of human food, and control of plankton in nutrient-rich ponds and wastewater treatment plants.

Economic value

Global aquaculture production of Hypophthalmichthys molitrix has grown steadily over time with just over 400,000 tonnes being produced in 1980, 1.5 million tonnes in 1990, 3 million tonnes in 2000, over 4.7 million tonnes in 2017 (FAO, 2019b) and over 4.8 million tonnes in 2019 (FAO, 2021). The species is now one of the major species produced in world aquaculture, third only to grass carp (Ctenopharyngodon idella) and the shrimp Penaeus vannamei; it accounted for 10% of world production in 2016 (Food and Agriculture Organization, 2018).

The majority of production of Hypophthalmichthys molitrix takes place in China, where 3.8 million tonnes were produced in 2019; India (0.5 million tonnes) is the second largest producer. The species is cultured in a number of other countries around the world; Russia is the largest producer in Europe with 39,000 tonnes (compared to nearly 70,000 tonnes for the common carp, Cyprinus carpio) (FAO, 2021).

Environmental Services

Although Hypophthalmichthys molitrix has often been introduced for plankton control, its ability to control algal blooms is rather controversial, because it can efficiently filter algae >20 µm in size, so the number of the smaller algae increases as a result of lack of grazing by the fish and increased nutrients. Some noxious blue-green algae are controlled by H. molitrix (and H. nobilis), but others are not and can even be exacerbated (because they pass through the gut of the fish unharmed, and pick up nutrients on the way). Also, consumption of zooplankton and larger and colonial phytoplankton leaves an open niche that is often filled by nanophytoplankton. Research has been conducted exclusively in lakes, so the effects in river ecosystems are unknown (Oregon State University, 2010).

Pillay (1993) suggested that Hypophthalmichthys molitrix could be of considerable value in controlling algal blooms and reducing oxygen consumption. Domaizon and Devaux (1999) reported that it was efficient in controlling algal blooms if the right number of fish was used.

Radke and Kahl (2002) suggested that Hypophthalmichthys molitrix should be used only if the primary aim was to reduce nuisance blooms of large phytoplankton species, e.g. cyanobacteria, that cannot be effectively controlled by large herbivorous zooplankton. They concluded that stocking of H. molitrix appears to be most appropriate in tropical lakes that are highly productive and naturally lack large cladoceran zooplankton.

Leventer and Teltsch (1990) were more in favour of using Hypophthalmichthys molitrix to control not only algae but also zooplankton and suspended organic matter. They claimed that introducing 300-450 silver carp/ha in the Netofa reservoirs in Israel created a balanced ecological system.

Starling (1993) used a biomass of 41 g/m³or 850 kg/ha of Hypophthalmichthys molitrix in a mesocosm experiment in the eutrophic Paranoa reservoir in Brasilia, Brazil, to assess its impact on the plankton community and water quality. He found that H. molitrix significantly reduced micro-zooplankton (copepod nauplii and rotifers <200 µm), metaphytoplankton >20 µm and total phytoplankton biomass. Apart from increased nitrogen in the sediments, nutrient and chemical properties of the water were not affected by fish presence.

Dabbadie (2005) lists two advantages of introducing Hypophthalmichthys molitrix in aquaculture:

1. Avoidance of some trophic deadlocks. When a dense stock of common carp (Cyprinus carpio) is raised in monoculture, a small crustacean, Bosmina (Bosmina) longirostris develops and is considered harmful as it feeds on phytoplankton and is not grazed by common carp; it competes with other herbivorous zooplanktonic organisms which otherwise would be consumed by the common carp. When H. molitrix is introduced in polyculture with common carp, B. longirostris declines as a consequence of the grazing of H. molitrix.

2. In ponds, improvement of oxygenation occurs due to the presence of Hypophthalmichthys molitrix or tilapia. H. molitrix consume excess algae which otherwise could create an imbalance between production and consumption of oxygen.

Uses List

Human food and beverage > Live product for human consumption

Human food and beverage > Whole

Animal feed, fodder, forage > Live feed

Environmental > Biological control

Human food and beverage > Food

Human food and beverage > Meat/fat/offal/blood/bone (whole, cut, fresh, frozen, canned, cured, processed or smoked)

Products

Processing and Products

Hypophthalmichthys molitrix is generally eaten as normal fish meat, although Safari and Yaghoubzadeh (2015) investigated its use to produce 'fish cheese'.

As well as its use in aquaculture as a source of human food, Hypophthalmichthys molitrix has been widely introduced around the world to control plankton in nutrient-rich ponds and wastewater treatment plants, although its effectiveness for this is not universally accepted.

Prevention and Control

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

To reduce the spread of Hypophthalmichthys molitrix, in 2007 the US Fish and Wildlife Service added it to the federal list of injurious species (US Fish and Wildlife Service, 2022). The fear that this species may make its way to the Great Lakes and interrupt the US $4 billion fishing industry has prompted the US Army Corp of Engineers and the state of Illinois to build (at a cost of 10 million dollars) an electric barrier on the Chicago Sanitary and Ship Canal to stop it moving from the Mississippi River watershed into the Great Lakes watershed.

Because of the damage caused by Hypophthalmichthys molitrix in the United States, Canadian people and authorities have been trying to prevent its spread to their waterways, especially in the Great Lakes area. Hence, the Great Lakes Fisheries and Ontario Federation of Anglers and Hunters (OFAH) (http://www.ofah.org) have been trying to raise public awareness of the negative impact of the species on wildlife and the possibility of its spread from the USA. The eight Great Lakes states (and the Province of Ontario in Canada) are working together to develop a policy framework to prevent Asian carps from invading the Great Lakes. Importation, rearing and/or trade of live H. molitrix are severely restricted in most of these states.

Donaldson et al. (2016) tested the effectiveness of infused carbon dioxide gas as a tool to deter the movement of non-native big-headed carps, and suggest that carbon dioxide may provide an effective tool in enhancing existing control measures (such as electrical barriers) for such high-risk invasive fish, in particular for keeping them out of the Laurentian Great Lakes.

Although it is thought that there are no self-sustaining populations of Hypophthalmichthys molitrix in New Zealand (NIWA, 2005), importation of broodstock of this species to New Zealand for breeding is not permitted.

Behaviour

Hypophthalmichthys molitrix typically swims just beneath the water surface (Man and Hodgkiss, 1981). It is an active species and is well known for its habit of leaping clear of the water when disturbed (Skelton, 1993). This behaviour is observed when broodstock are picked up for breeding at the hatchery -- they try to jump out of the broodstock tank. Tanks are covered with netting to stop them from jumping out, and low doses of anaesthetic and cool water have proved to be effective in calming them down during transport to the hatchery. However despite all the above precautions the fish still become exhausted and sometimes die (T Kurwie, Mahurangi Technical Institute, New Zealand, personal observation, 2004).

Feeding Behaviour

Hypophthalmichthys molitrix is well recognized as a filter feeder. Its highly modified gill apparatus enables it to do this efficiently, as does its greatly elongated alimentary canal which enables it to properly digest this food. It is reported to be able to filter 10-16% of its body weight in plankton per day at moderate water temperatures; feeding ceases at low temperatures and activity increases with rising temperature. Growth rates are closely related to water temperatures (McDowall, 1990). The species feeds best in eutrophic waters where phytoplankton densities are very high, often such that the water has a distinctly green coloration and a high level of turbidity. Feeding is not restricted entirely to filtering plankton from the water, as the fish are also observed also to feed on the concentrated algal mass or scum at the surface of the water. It has been reported that adult silver carp efficiently graze on phytoplankton (particles more than 20 µm) and that zooplankton is an essential source of food for this species (Domaizon and Devaux, 1999). In Lake Kinneret in Israel, they feed on phytoplankton from February to August and predominately on zooplankton from September to January, a response to a decrease in phytoplankton biomass in summer to autumn. Cladocerans and cyclopoid copepods dominate the biomass of zooplankton taken (Spataru and Gophen, 1985). The ability to take cyclopoids is due to the large mouth, strong sucking power and high filtration rate when feeding. Food is taken passively rather than selectively (Coad, 2004).

Reproductive Behaviour

In its natural range, Hypophthalmichthys molitrix migrates upstream to breed. It requires cool flowing water to breed. Spawning takes place after a sharp rise in water level and current speed. It breeds naturally in the flowing rivers of China during April-July. In the Tone River of Japan, where it has established itself, it spawns naturally during June-July. In the Terek River of Dagestan in the Caucasus region of southern Russia, the spawning migration begins at the end of April at 16-17°C, with a peak between the middle of May and the beginning of June. Eggs are first found in the drift in the second week of June (Coad, 2004). Spawning in the Syr Darya River, Kazakhstan was reported to occur in April-May at temperatures between 18-22°C; the fish spawn in small group of 15-25 at dusk and dawn (Alikunhi, 1963; Kamilov and Salikhov, 1996).

The species does not spawn naturally in ponds and tanks in many parts of the world. In New Zealand, it is found in the wild but is not thought to be able to breed naturally (McDowall, 2000; Chadderton et al., 2003). In Cuttack, India, pond-reared fully ripe males were reported to be available during April-May, and females a little later, during May-July (Alikunhi, 1963, from Jhingran and Pullin, 1988).

Reproduction

Hypophthalmichthys molitrix breeds naturally only in the flowing waters of its natural habitat, in rivers in association with the monsoon floods (Jhingran and Pullin, 1988). Induction of sexual maturation and spawning by hormone manipulation is a commonly used practice nearly all over the world where this species has been introduced for food and/or biological control of phytoplankton blooms. Artificial propagation is also practised in countries where it can breed naturally. This practice is preferred for its merits in producing higher quality offspring and higher hatching, fertilization and survival rates.

Broodstock culture conditions

For successful breeding, broodstock are conditioned in ponds for several months preceding the breeding season. They should be kept in ponds rich with plankton, which is necessary for yolk formation (W.L. Shelton, University of Oklahoma, USA, personal communication, 2005). They prefer small fertilized ponds with a good growth of phytoplankton; sometimes they are fed soybean flour or rice bran (Pillay, 1993).

Close monitoring of the water quality during egg maturation after hormonal injection is vital for successful breeding. Parameters include:

•

dissolved oxygen more than 5 mg/L

•

temperatures of 22-24ºC

•

water flow of 4 L/kg body weight

(L Horvath, University of Agricultural Sciences, Hungary, personal communication, 2005).

Induced Spawning, Stripping and Fertilization

Natural spawning of Hypophthalmichthys molitrix only occurs in rivers. Even when it is possible to simulate the riverine environmental conditions, the ripe broodfish can be made to spawn in tanks and basins only by hormone induction, and even then, only ovulation can be induced by this method and sexual products have to be stripped and fertilized artificially. Full spontaneous spawning is hardly ever achieved. Only about 50-70% of the eggs may be released, and the rest (30-50%) will be spoiled unless the fish is stripped in time (50 min).

Various hormones such as carp pituitary extract (CPE), human chorionic gonadotropin (HCG) and luteinizing hormone releasing hormone (LHRH) are concurrently used to induce final maturation and spawning in freshwater fish including Hypophthalmichthys molitrix. The choice of hormone depends on availability, hatchery regime and economy of use, but in most hatcheries, a combination of two hormones is a common practice; the most common is a combination of CPE and HCG.

For stripping, the fish should be anaesthetized and thoroughly dried with a clean towel, taking care not to let any water get in contact with the stripped eggs. After stripping, eggs remain fertile for 10-20 min if free from water; in freshwater they lose their fertility in 1 min. Sperm of silver carp are only active after they are released into the water. In freshwater, sperm survive for 1 min and are at their most fertile for the first 23-30 seconds; in normal saline conditions they survive for 2-3 min.

There are two methods of artificial fertilization: the dry method and the semi-dry method. In the dry method, about 15 min after the beginning of oestrus, the broodfish is captured and stripped. The eggs are collected in a basin (no more than 500,000 eggs in one basin). The milt is either directly squeezed on to the eggs or transferred with a pipette and dropped onto the eggs. In the semi-dry method, the milt is diluted with a little normal saline and transferred onto the eggs by pipette (Yu, 1989; Horvath et al., 1992).

Sperm

Hypophthalmichthys molitrix sperm consists of a head, neck and tail. The head is almost spherical, 2.2-2.5 µm in diameter, consisting of an apex and nucleus. The apex is situated at the front of the head. The neck is about 1.1 µm; the tail is narrow and 35 µm long. The tail is the metabolic centre and motor organ. 1 ml of milt contains 48 million sperm. The total amount of milt exuded from one male can reach 30-40 ml (Peirong, 1989).

Eggs

(Information from Jhingran and Pullin (1988) and Peirong (1989)).

Hypophthalmichthys molitrix is quite a fecund species. The fecundity of fish weighing 3.18-8.51 kg was 145,000-2,044,000. The average number of eggs per g of body weight was 171 and that per g ovary weight was 292.

The eggs are non-sticky and semi-buoyant. Those of yearling silver carp, weighing up to 2.4 kg, measured 1.20 mm in diameter, whereas those of four-year-old fish were about 11% larger. The fertilized eggs absorb water and their membrane expands to about 5-6 mm in diameter due to their large perivitelline space. Fully swollen, water hardened eggs had a volume of about 0.07 ml.

Having a greater specific gravity than water, the eggs sink to the bottom in still water, but they are semi-buoyant in currents, floating until the fry hatch. The optimum incubation temperature is 22-28ºC. The eggs hatch 34-70 h after fertilization depending on the temperature; in hatcheries they hatch in as little as 24 h at temperatures of 23-28°C). Hatchlings weigh approximately 0.0031 g after they absorb their yolk sac.

Hormones for inducing spawning of Hypophthalmichthys molitrix in some countries around the world:

Country	Water temp (C°)	Hormone (route)	First Injection	Second injection	? T (hr)	Latency (hr)	Source
Israel		CPE (IM)					Jhingran and Pullin (1988)
Malaysia		CPE or P. gonionotus pituataries (IM or IP)	F: 5-6 mg/kg	F: 5-6 mg/kg	5	5-6	Jhingran and Pullin (1988)
Malaysia	25-27	HCG+CPE	F: 200 IU HCG/kg	F: 4 mg/kg CPE	6	6-7	Jhingran and Pullin (1988)
China	20-28	LHRH-A	F: 8-10 µg/kg		22-24		Jhingran and Pullin (1988)
India	28-34	pituitaries (IM)	F: 4 mg/kg	F: 6-10 mg/kg. M: 2-3 mg/kg		4-5	Jhingran and Pullin (1988)
Thailand	27-33	CPE (IM)	F and M: 0.23-1 pituitary	F: 1-34 pituitaries plus 20 rabbit units Synahorin	6-8	4-6	Jhingran and Pullin (1988)
China	20-30	domperidone 5 mg/kg + LHRHa 50 µ/kg				8-12	Peter et al. (1988)
China	20-30	HCG	100-200 IU/kg	700-1000 IU/kg or 400 IU + 10 µ/kg LHRHa	6	6-8	Peter et al. (1988)
Malaysia		HCG (first and second injection); CPE (third injection)	50 IU/kg	250 IU/kg; 3^rd injection 4 mg/kg CPE	24 + 6		Argent Laboratories (2004)
Malaysia		CPE	5 mg/kg	10 mg/kg	6		Argent Laboratories (2004)
China		CPE	2-4 mg	10-20 mg/kg	5 or 6		Peter et al. (1988)

Growout Management Table

Ecosystem	Growout systems	Inland	Coastal	Adult stocking density (/m³)
Ecosystem	Growout systems	Inland	Coastal	Extensive	Semi-intensive	Intensive
Irrigation canals	Ponds	Yes
Pig farms	Ponds	Yes
Poultry farms (ducks, fowls and turkeys)	Ponds	Yes
Reservoirs		Yes
Ricefields		Yes
Rivers/streams		Yes
Rural areas		Yes

Growout Management

The natural habitat of Hypophthalmichthys molitrix is (except for spawning) standing or slow-flowing conditions such as in impoundments or the backwaters of large rivers.

Polyculture

Hypophthalmichthys molitrix is more commonly reared as a polyculture species (accounting for 50-63% of fish with other cyprinids such as grass carp, Ctenopharyngodon idella, and common carp, Cyprinus carpio) (Food and Agriculture Organization, 1999). This is an efficient production system for maximum utilization of the pond ecosystem, as the fish feed at different levels. 6 tonnes/ha can be produced yearly by fertilizing and by adding manure to the pond. This kind of culture is mainly practised in China (especially with H. molitrix and the bighead carp, Hypophthalmichthys nobilis), with the major Indian carp on the Indian subcontinent, and to a lesser extent in other Asian countries and eastern Europe. There are several other factors advocating the use of polyculture besides the commercial value of the species; for example the breeding and feeding habit of the fish, the climate, fertilization practice and pond conditions are some of the factors affecting which species to culture (Woynarovich and Horvath, 1980). The table below gives examples of polyculture in some countries worldwide, showing the number of fish stocked per 100 m² of pond surface area (Bocek, 2019):

Species	China	India	Malaysia	Thailand				Panama	Sierra Leone
Bighead carp (Hypophthalmichthys nobilis)	1		1	3				10
Silver carp (H. molitrix)	12		1	3
Grass carp [Ctenopharyngodon idella]	2		3	3
Common carp (Cyprinus carpio)	17		1	6	32	31		10
Tawes (Barbonymus gonionotus)				63	63	63
Rohu (Labeo rohita)		38		6
Mrigal (Cirrhinus cirrhosus)		6
Catla (Catla catla or Gibelion catla)		19
Tilapia				63	63	63	125	100	160
Ophicephalus [Channa]							3
Cichlasoma								20
Notopterus									16

Dabbadie (2005) lists two advantages of including Hypophthalmichthys molitrix with other species in aquaculture, resulting from its consumption of plankton:

Temperature

Hypophthalmichthys molitrix can live between 0.5 and 38°C, with an optimum range of 25-32°C for food intake and growth. Feeding declines when the temperature drops below 15ºC and stops below 5-7ºC. The fish begin to die at temperatures below 0.5°C and above 40°C (Verigin et al., 1978).

Water Quality

Hypophthalmichthys molitrix prefers a slightly alkaline environment (pH 7.5-8.5). Growth will be retarded outside this range. The higher the dissolved oxygen content (DOC) the greater the feeding intensity. At DOC above 4-5 mg/L feeding is intense, growth is fast and food conversion factor is low. With the DOC below 2 mg/L, the fish lose their appetite; below 1 mg/L they stop feeding and gasp for air and below 0.5 mg/L they will suffocate and die (Verigin et al., 1978).

Natural Food Sources

Food source	Life stages	Contribution to total food intake (%)
Brachionus (rotifer)	Aquatic\|Larval
flagellates, Dinoflagellata (Dinophyta), Myxophyceae, Bacillariophyceae	Aquatic\|Adult Aquatic\|Fry
phytoplankton (Oscillatoria, Aphanizomenon)	Aquatic\|Adult	80
zooplankton (copepods, cladocera) and phytoplankton	Aquatic\|Fry
Copepod nauplii	Aquatic\|Larval

Artificial Food Sources

Food source	Life stages	Contribution to total food intake (%)	Feeding methods	Feeding frequency	Feeding characteristics	Details
wheat or rice bran, bean cake, peanut cake	Broodstock		spread on the surface of pond	twice daily	fine float or sink

Fertilizers

Fertilizer type	Life stages	Unintentional	Intentional	Details
ammonium nitrate or urea (carbamide), or ammonium sulphate in alkaline water	Adult Fry	Unknown	Yes
organic fertilizer (cow, pig, chicken manure)		Yes	Yes

Nutrition and Feeding

One-to-three-day-old fry, when about 7-9 mm long, mainly feed on zooplankton, in particular rotifers and copepod nauplii. Their diet expands as they grow to include copepods, cladocerans and phytoplankton. Still larger fry and adults feed on flagellates, Myxophyceae, Bacillariophyceae, etc., primarily phytoplankton and then zooplankton (Jhingran and Pullin, 1988).

Ponds may be fertilized with animal manure, or ammonium/urea fertilizers, to encourage the growth of plankton.

Broodstock may be fed with wheat or rice bran, or bean or peanut cake.

Genetics Table

Country	Locality	Haploid	Diploid	Markers	References
China	China	24	48	n	FishBase (2005)
China	Wuhan City, Hubei Province	24	48	y	FishBase (2005)
India	Kalyani, West Bengal	24	48	n	FishBase (2005)
Uzbekistan	Tashkent	24	48	n	FishBase (2005)
Uzbekistan	Uzbekistan		48-56	n	FishBase (2005)
Croatia	Zagreb	24	48	n	FishBase (2005)
Hungary	Hungary	24	48	n	FishBase (2005)
Russian Federation	Reservoir Tsimlyanskoe		46-58	n	FishBase (2005)
Ukraine	Kiev	24	48	n	FishBase (2005)

Electrophoretic Studies

Country	Locality	Total loci	Observed	Expected	Polymorphic loci	References
USA	Alabama Agricultural Experimental Station, Auburn University, Alabama, USA	23		0.0439	0.130	FishBase (2005)

Performance

Of all the environmental factors, temperature exercises the greatest effect on the maturity of Hypophthalmichthys molitrix. The table below shows the difference in the age and weight of the adults at sexual maturity in different geographical regions of China and Romania. In the Iranian River Terek, H. molitrix usually first mature at 4 years of age for males and 5 years for females. About 15% of females mature at 4 years of age but 87% of the females and 85% of the males do so in the 5-7 age groups (Coad, 2004). Growth rates are also closely related closely to water temperatures (McDowall, 1990).

Table: Age and size at sexual maturity of silver carp (Jhingran and Pullin, 1988).

Country	Age (years)	Weight (kg)	Reference
South China	2-3	2-5	Kuronuma (1968)
Central China	4-5	2-5	Kuronuma (1968)
North China	5-6	2-5	Kuronuma (1968)
Romania	6-9	6-8	Woynarovich (1968)

Marketing

Almost the entire production of carp is for domestic markets for local consumption.

Economic and Socioeconomic Aspects

Production, Economic and Socioeconomic Aspects

Related Case Studies (Cultured Aquatic Species)

Links to Websites

Name	URL	Comment
Fisheries and Oceans Canada -– Silver Carp	https://www.dfo-mpo.gc.ca/species-especes/profiles-profils/silvercarp-carpeargentee-eng.html
GISD/IASPMR: Invasive Alien Species Pathway Management Resource and DAISIE European Invasive Alien Species Gateway	https://doi.org/10.5061/dryad.m93f6	Data source for updated system data added to species habitat list.
Global Invasive Species Database	http://www.iucngisd.org/gisd/
Global register of Introduced and Invasive species (GRIIS)	http://griis.org/	Data source for updated system data added to species habitat list.
USGS Silver Carp Fact Sheet	https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=549

References

Alam, M. M., Khan, M. A., Hussain, M. A., Moumita, D., Mazlan, A. G., Simon, K. D., 2012. Intensity of parasitic infestation in silver carp, Hypophthalmichthys molitrix.Journal of Zhejiang University (Science B), 13(12) 1024-1028.

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Subject Areas

Resources

Tools

Evidence & Policy

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Abstract

Identity

Pictures

Overview

Summary of Invasiveness

Taxonomic Tree

Description

Pathogens Carried

Distribution

Distribution Map

Distribution Table

History of Introduction and Spread

Introductions

Risk of Introduction

Anatomy

Dentition

Gills

Digestive System

Reproductive System

Skeleton

Habitat List

Climate

Air Temperature

Water Tolerances

Diseases, Disorders and Natural Enemies

Anchor worm disease (Lernaea sp.)

Gill fluke disease

Trichodinosis

Whirling disease

Enteric redmouth

Vertical scale disease

Spring viraemia of carp

Predation

List of Diseases and Disorders

Natural enemies

Impact Summary

Impact: Economic

Impact: Environmental

Impact: Social

Risk and Impact Factors

Invasiveness

Impact outcomes

Impact mechanisms

Likelihood of entry/control

Uses

Economic value

Environmental Services

Uses List

Products

Processing and Products

Prevention and Control

Behaviour

Feeding Behaviour

Reproductive Behaviour

Reproduction

Broodstock culture conditions

Induced Spawning, Stripping and Fertilization

Sperm

Eggs

Growout Management Table

Growout Management

Polyculture

Temperature

Water Quality

Natural Food Sources

Artificial Food Sources

Fertilizers

Nutrition and Feeding

Genetics Table

Electrophoretic Studies

Performance

Marketing

Economic and Socioeconomic Aspects