Fish farming is an agricultural activity that can deeply improve already
existing farming systems. For example, it can increase the water availability
to other cultures or it can increase the farm income when livestock is
associated or when cultures are conducted in the pond itself (rice when
full, other cultures when drained). On the other side, fish farming can
also benefit from agricultural by-products generated by other activities,
as they can be used to increase the quantity of plankton, that is the natural
food of fish. But in return, the management of such an integrated fish
farm is complex and implies to respect some standards.
The objective is to obtain a high fish production with numerous positive
impacts on the other activities, using as much as possible resources available
on the farm. For the fish production, the technical results are a quick
growth and a high yield. The economical results are the income and the
profit, which are not always lineary linked to the technical results.
Several factors will influence the success or failure of an integrated
fish farming activity :
The quality of the ponds. For many people, a fish pond is only a water
body, but in fact, it is not. The technology for building ponds has made
many progress. The front dyke must be large enough to avoid water and nutrient
loss by seepage. The pond bottom declivity must be high enough to allow
a complete and rapid draining, in particular at the end of the emptying
operation when the fish suffer from the low water quality. In some cases,
the pond profile has to be adapted to the culture of complementary productions
during fish growth (rice) or draining.
The fish density (number of fish per surface unit). The fish density must
be adapted to the amount of food (natural and artificial) available. With
a given feeding level, when the density is too high, the growth stops ;
when it is too low, the yield is bad.
The fish polyculture (culture of several fish species in the same pond).
In an integrated fish farm, fish production relies mainly on the natural
food, even if an artificial food is used. It is then convenient to use
fish species with complementary feeding regimes (herbivory, benthivory,
planktivory etc.), in order to exploit all available trophic resources.
This is called polyculture. Some interactions between different fish species
may even promote a better growth than if each fish was to be produced separately
(for example, tilapia provide a better oxygenation of water, which benefits
other species). But some other interactions are negative and induce a decrease
of the fish production (trophic competition between fish species). The
ratio between all the species is then to be clearly identified.
The pond fertilization. It is possible to increase the quantity of natural
food by fertilizing the water. The fertilizerís or manureís organic and
mineral nutrients are used by bacterias and plants, mostly micro-algae,
which are then consumed by filtrating organisms, mostly zooplankton. All
these organisms are then eaten by fish, so that the production is greatly
improved. Chemical fertilizers are efficient at a low dose, but some can
induce toxicity problems. Organic fertilizers are cheap but can induce
oxygenation problems, as a consequence of the microbial degradation of
the organic matter it contains. Organic fertilizers can be applied by breeding
livestock in shed over or near the pond.
The management of other cultures and livestock. The production of other
cultures in association to fish farming relies mainly on each cropís traditional
technologies, but some factors, in particular the variety, may be adapted.
The use of some pesticide can also be restricted if it may kill fish or
reduce its growth. In the case of an integration aquaculture-livestock,
the animal quantity must be defined. For pigs, livestock generally recommended
are 30 to 85 pigs.ha-1 and for ducks, 1000 to 3500 ducks.ha-1.
The main constraint is related to the fact that the farmers have to master
perfectly the two breedings.
The main cost is the construction of the pond, although many small farmers,
with low financial resources but high working capacity during seasons where
work on other cultures is reduced, can construct it themselves.
The most important cost during the production is the artificial food,
but it isnít so frequently used on integrated fish farms, as fertilization
alone is very efficient and is more widely employed. Manure is cheap and
efficient but the quantities needed to obtain a good production are so
important that they make its use uneconomical if they are not available
in the proximity of the farm and need to be transported. Mineral fertilizers
are more expensive but sometimes, their use is economically more profitable.
Targeted Livestock Systems
Farming system with aquatic ecosystem management
Positive environmental impact
Improved use of all available farm resources.
Promotion of locally available manure and agriculture by-products.
With some endangered fish species (Arapaima gigas for example),
diminution of the fishery pressure on wild populations.
Monitoring: EIA, indicators
Negative environmental impact
Water pollution (eutrophication) in case of excessive fertilization or
if many farms are in production in the region.
Low oxygen content of water in case of excess of organic fertilization.
Water turbidituy and colour: Secchi disk (black and white disk used to
determine the turbidity by measuring the deepness at which the disk disappears
when introduced in water).
Intermediary growth and yield determination using sampling.
Billard R., 1995. Les carpes: biologie et élevage. INRA,. Paris,
France : pp. 387.
Hepher B., Pruginin Y., 1990. Commercial fish farming. John Wiley &
sons, New York, USA. pp. 261.
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