3. సైట్ ఎెంపిక:
• Site selection:
• Soil Influences both Productivity & Water quality in a pond.
• Soil texture: Soil particle size composition.
• Porosity or permeability:
• నీటిని ఉత్తేజపరచటానికి సామర్యం.
చెరువు దిగువన నీటిని కలిగి ఉండాలి (బంకమటిి వంటి తకకువ సచ్ఛిద్రత కలిగి
ఉంట ంది) & మటిి కూడా పో షకాలను అందించడం దాారా నీటి సంత్ానోతపత్తే
దోహద్ం చతయాలి (మటిి నిరాాణం చాలా మటిి కణాలక కలిగి) కాబటిి చెరువు
నిరాాణం కోసం ఉతేమ మటిి కలే కలిగి ఉంది.
• Ability to let water pass through.
• The pond bottom must be able to hold water (have a low porosity like clay)
& the Soil should also contribute to the fertility of the water by providing
nutrients (soil texture consists of a lot of clay particles) so the best soil for
pond construction contains of a Clay.
• 3 ways should follow to predict whether the soil for pond construction are
A) the Squeeze method. B) Ground water test. C) Water permeability test.
4. • Soil ఒక చెరువులో ఉత్ాపద్కత మరియు నీటి
నాణయతను మటిి పరభావితం చతసుే ంది.
5. Squeeze method
• Squeeze method:
• Wet a handful of soil with just enough water to make it
moist.
• Squeeze the soil & if it holds its shape after opening the palm
of your hand, the soil will be good for pond construction.
• 2) Ground water test:
• A) dig a hole with a depth of one meter.
• B) cover it with levels for one night to limit evaporation.
• C) if the hole is filled with ground water the next morning a
pond could be built. Take into account that you will probably
need more time to drain the pond due to the high ground
water levels filling the pond again.
• D) if the hole is still empty the next morning, no problems
will occur as a result of high ground water levels and the site
will perhaps be suitable for pond fish farming. Now you
should test water permeability.
6. Water permeability test
• Fill the hole with water to the top
• Cover the hole with leaves
• The next day the water level will be lower due to
seepage. The dikes of the hole have probably
become saturated with water and might hold water
better now.
• Refill the hole with water to the top
• Cover it once more with leaves. Check the water
level the next day
• If the water level construction.
• If the water has disapperared again the site is not
suitable for fish farming unless the bottom is first
covered with plastic or heavy clays.
9. Eradication of Aquatic weeds and Removal predatory fishes
• Aquatic weeds are unwanted and undesirable vegetation that reproduce
and grow in water. If left unchecked may choke the water body posing a
serious manace to pisciculture.
• They provide breeding grounds and harbour predatory insects.
• Provide shelter to predatory and weed fishes and molluscs.
• They restrict free movement of fry.
• They cause obstruction during netting.
• Limit living space for fish
• Limit plankton production
• Reduce sunlight penetration and nutrients.
• Upsets the equilibrium of physico-chemical properties of water.
• Cause imbalance in dissolved oxygen budget.
• Promote accumulation of deposits leading to siltation
• Reduce water movement, thereby limits oxygen circulation in water.
• Some weeds release toxic gases that cause fish death and add foul smell
to water.
10. Removal of aquatic weeds
• Removal of aquatic weeds
• All these weeds have to be eradicated using one or more of the following
methods.
• 1. Manual method
• Manual removal of weeds involves physical removal of the weeds by hand.
This may be practical if the pond is small and labour is cheap.
• 2. Mechanical method
• Some machines or implements are used for removing aquatic weeds. This
method is normally applicable for larger water bodies. It is capital
intensive and beyond the means of average fish farmer.
• 3. Chemical method
• Weeds are eradicated using chemicals.
• Different weedicide are used for removal of different weeds present in
aquaculture pond.
• Common weeds and the weedicides for their control
11. Biological Controlling Methods
• Biological method
• The method is more advantageous since the undesirable weeds are converted into fish flesh.
• It is cheap as no labour is involved and most suitable from the social and environmental point of view.
• The method employs certain organisms which feed on the weeds.
• The grass carp which can eat up much more aquatic vegetation is itself an excellent example of biological weed control.
• The common carp helps in uprooting of certain plants.
• Tawes, Puntius gonionotus is also a good feeder of aquatic weeds.
• The Yamuna turtle consumes water hyacinth in the ponds.
• Common weed eating fish and the weeds of their preference
• Fishes
• Names
• Feed upon
• Grass carp
• Ctenopharyngodon idella
• Submerged weeds e.g: Hydrilla, Najas , Ceratophyllum, Potamogeton, Otteliaand duck weeds
• Common carp
• Cyprinus carpio
• Tender shoots
• Gaurami
• Osphronemus goramy
• Tender shoots of submerged weeds and filamentous algae
• Pearl spot
• Etroplus suratensis
• Filamentous algae
• Silver carp
• Hypophthalmichthys molitrix
• Algal bloom
18. Combined intensive-extensive fish farming systems in Hungary. The
number of opportunities seems unlimited. Source: Laszlo Varadi, Research Institute
for Fisheries, Aquaculture and Irrigation (HAKI), Szarvas, Hungary.