Coastal Aquaculture and Mariculture (2+1)

Unit 6 - Culture of Crustaceans

6.1.5.a. Pond preparation

Ponds are prepared to improve control over pond conditions and to provide optmimum environment for optimum growth of shrimps.

Step-1: Flush out all the slurry from the previous crop repeatedly by keeping the inlets open. Pumps with nozzles can also be used to stir up sediments. This step should be carried out immediately after harvest.

Step-2: Seal all the inlets and outlets and allow the pond soil to dry for a minimum of 7-10 days till the soil can support the weight of a person. It should crack (sandy soils don’t crack). Drying facilitates oxidation of organic matter, ammonia, hydrogen sulphide, methane and ferrous iron, all of which are toxic to shrimps. Drying also disinfects the pond by killing pathogens. It eliminates unwanted fish eggs, crabs and other potential predators and competitors. Over drying should be avoided since it is counterproductive.

Step – 3: the pond soils should be limed to correct the pH of soil and water. Liming neutralizes acids in the soil, helps in decomposition of organic matter and sterilizes the soil killing pathogens. Calcium oxide, calcium hydroxide, calcium carbonate or dolomite can be used for liming the shrimp ponds.

Apply lime uniformly to the pond soil and till lightly.

Manual liming of ponds

Step – 4: Fill ponds with 30cm of water and leave for 3 days. Drain when colour becomes light green.

Step – 5: Apply urea @ 50-100Kg/ha and single super phosphate @ 7.5-15Kg/ha. This facilitates growth of diatoms which form good food for shrimp post larvae.

For modified extensive shrimp farming apply poultry manure or cow dung @ 1000-1500Kg/ha to facilitate growth of natural shrimp food.

Step – 6: Fill water 10cm every day up to a depth of 100-120cm. Check the water pH, it should be between 7.5and 8.5, if not correct using required quantity of lime. The pond should be ready for stocking in about 5-7 days. The following indicator should be used to judge whether the pond is ready to be stocked or not.

• Secchi disc reading 40-25cm
• Stable pH
• Algal blooms – the water should be brown with yellowish hue
• Water temperature should be above 25^oC.