A freshwater prawn farm is an aquaculture business designed to raise
and produce freshwater prawns or shrimp1 for human consumption.
prawn farming shares many characteristics with, and many of
the same problems as, marine shrimp farming. Unique problems are
introduced by the developmental life cycle of the main species (the
giant river prawn,
The global annual production of freshwater prawns (excluding crayfish
and crabs) in 2003 was about 280,000 tons, of which
some 180,000 tons, followed by
with some 35,000
tons each. Additionally,
produced about 370,000 tons of Chinese
river crab (Eriocheir sinensis).
2 Biology of
5 See also
8 External links
All farmed freshwater prawns today belong to the genus Macrobrachium.
Until 2000, the only species farmed was the giant river prawn
Macrobrachium rosenbergii, also known as the Malaysian prawn). Since
China has begun farming the Oriental river prawn (M. nipponense)
in large quantities, and
India farms a small amount of monsoon river
prawn (M. malcolmsonii). In 2003, these three species accounted for
all farmed freshwater prawns, about two-thirds M. rosenbergii and
one-third M. nipponense.
About 200 species in the genus
Macrobrachium live in the tropical and
subtropical climates on all continents except Europe and Antarctica.
Giant river prawns live in turbid freshwater, but their larval stages
require brackish water to survive. Males can reach a body size of
32 cm; females grow to 25 cm. In mating, the male deposits
spermatophores on the underside of the female's thorax, between the
walking legs. The female then extrudes eggs, which pass through the
spermatophores. The female carries the fertilized eggs with her until
they hatch; the time may vary, but is generally less than three weeks.
A large female may lay up to 100,000 eggs.
From these eggs hatch zoeae, the first larval stage of crustaceans.
They go through several larval stages before metamorphosing into
postlarvae, at which stage they are about 8 mm long and have all
the characteristics of adults. This metamorphosis usually takes place
about 32 to 35 days after hatching. These postlarvae then migrate back
There are three different morphotypes of males. The first stage is
called "small male" (SM); this smallest stage has short, nearly
translucent claws. If conditions allow, small males grow and
metamorphose into "orange claw" (OC) males, which have large orange
claws on their second chelipeds, which may have a length of 0.8 to 1.4
times their body size. OC males later may transform into the third and
final stage, the "blue claw" (BC) males. These have blue claws, and
their second chelipeds may become twice as long as their body.
Male M. rosenbergii prawns have a strict hierarchy: the territorial BC
males dominate the OCs, which in turn dominate the SMs. The presence
of BC males inhibits the growth of SMs and delays the metamorphosis of
OCs into BCs; an OC will keep growing until it is larger than the
largest BC male in its neighbourhood before transforming. All three
male stages are sexually active, though, and females which have
undergone their premating molt will cooperate with any male to
reproduce. BC males protect the females until their shells have
hardened; OCs and SMs show no such behavior.
Freshwater prawn farm in Bangladesh.
Giant river prawns have been farmed using traditional methods in
Southeast Asia for a long time. First experiments with artificial
breeding cultures of M. rosenbergii were done in the early 1960s in
Malaysia, where it was discovered that the larvae needed brackish
water for survival. Industrial-scale rearing processes were perfected
in the early 1970s in Hawaii, and spread first to
Taiwan and Thailand,
and then to other countries.
The technologies used in freshwater prawn farming are basically the
same as in marine shrimp farming. Hatcheries produce postlarvae, which
then are grown and acclimated in nurseries before being transferred
into growout ponds, where the prawns are then fed and grown until they
reach marketable size. Harvesting is done by either draining the pond
and collecting the animals ("batch" harvesting) or by fishing the
prawns out of the pond using nets (continuous operation).
Due to the aggressive nature of M. rosenbergii and the hierarchy
between males, stocking densities are much lower than in penaeid
shrimp farms. Intensive farming is not possible due to the increased
level of cannibalism, so all farms are either stocked semi-intensively
(4 to 20 postlarvae per square metre) or, in extensive farms, at even
lower densities (1 to 4/m²). The management of the growout ponds must
take into account the growth characteristics of M. rosenbergii: the
presence of blue-claw males inhibits the growth of small males, and
delays the metamorphosis of OC males into BCs. Some farms fish off the
largest prawns from the pond using seines to ensure a healthy
composition of the pond's population, designed to optimize the yield,
even if they employ batch harvesting. The heterogeneous individual
growth of M. rosenbergii makes growth control necessary even if a pond
is stocked newly, starting from scratch: some animals will grow faster
than others and become dominant BCs, stunting the growth of other
FAO considers the ecological impact of freshwater prawn farming to
be less severe than in shrimp farming. The prawns are cultured at much
lower densities, meaning less concentrated waste products and a lesser
danger of the ponds becoming breeding places for diseases. The growout
ponds do not salinate agricultural land, as do those of inland marine
shrimp farms. However, the lower yield per area means that the income
per Ha is also lower and a given area can support fewer humans. This
limits the culture area to low value lands where intensification is
Freshwater prawn farms do not endanger mangroves, and
are better amenable to small-scale businesses run by a family.
However, like marine farmed shrimp, M. rosenbergii is also susceptible
to a variety of viral or bacterial diseases, including white tail
disease, also called "white muscle disease".
The global annual production of freshwater prawns in 2003 was about
280,000 tonnes, of which
China produced some 180,000 tonnes, followed
Thailand with some 35,000 tonnes each. Other major
producer countries are Taiwan, Bangladesh, and Vietnam. In the United
States, only a few hundred small farms for M. rosenbergii produced
about 50 tonnes in 2003.
The technologies used in freshwater prawn farming, but also the
ecological problems associated with this industry, are basically the
same as for marine shrimp farming and are discussed in that article.
^1 The terminology is sometimes confusing as the distinction between
"shrimp" and "prawn" is sometimes blurred. Recent aquaculture
literature increasingly uses the term "prawn" only for the freshwater
forms of palaemonids and "shrimp" for the marine penaeids.
The main reference for this article was a comprehensive farming manual
of the FAO.
^ a b New, M. B.: Farming
FAO Fisheries Technical
Paper 428, 2002. ISSN 0429-9345.
^ a b Data extracted from the
FAO Fisheries Global Aquaculture
Production Database for freshwater crustaceans. The most recent data
sets are for 2003 and sometimes contain estimates. Accessed June 28,
^ Wynne, F.: Grow-out Culture of
Freshwater Prawns in Kentucky, 2000.
Last accessed July 4, 2005.
^ FAO: Cultured Species Fact Sheet M. rosenbergii; accessed June 30,
2005. Has images.
^ Tonguthai, K.: Diseases of the
Freshwater Prawn, Macrobrachium
rosenbergii, AAHRI Newsletter 4(2), Aquatic Animal Health Research
Institute, Bangkok University; December 1997.
^ Sahul Hameed, A. S.: White tail disease of Macrobrachium
rosenbergii, NACA, 2003.
^ Sahul Hameed, A. S.: White Tail Disease - Disease Card, NACA, 2005.
Aquaculture and the Environment
- An Environment Impact Assessment Report Archived 2011-07-16 at the
Wayback Machine., ch. 2; IAA report, April 2001.
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