Friday, November 8, 2024
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മലയാളം
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Water Management
Water quality and supply
Freshwater is normally used for rearing freshwater prawns from postlarvae to market
size. Water of 3-4 ppt salinity may be acceptable for the culture of M. rosenbergii.
The reliability of the quality and quantity of the water available at the site is
a critical factor in site choice. However, as in the case of hatchery water supplies,
the absolute ‘ideal' for rearing sites may be difficult to define; a range
of water qualities may be generally suitable. As for hatchery water, the level of
calcium in the freshwater seems to be important. Growth rate has been reported to
be lower in hard than in soft water. It is recommended that freshwater prawn farming
should not be attempted where the water supply has a total hardness of more than
150 mg/l (CaCO3).
Water quality requirements for prawn nursery and
grow out
Variables
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Recommended range
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Temperature (oC)
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28-31
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pH
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7.0-8.5
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Dissolved oxygen (ppm)
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3-7
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Salinity (ppt)
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<10
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Transparency (cm)
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25-40
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Alkalinity (ppm)
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25-60
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Total hardness (ppm)
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30-150
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Ammonia (ppm)
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<0.3
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Nitrite (ppm)
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<2.0
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Nitrate (ppm)
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<10
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Boron (ppm)
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<0.75
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Iron (ppm)
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<1.0
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Copper (ppm)
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<0.02
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Manganese (ppm)
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<0.10
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Zinc (ppm)
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<0.20
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Hydrogen sulfide (ppm)
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Nil
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(Source: Food and Agriculture Organisation, 2002)
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