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A successful aquaculture practice with a good harvesting is usually due to proper construction preparation and maintenance of the fish pond.
Within the fish farming pond system there can be different pond components, namely nursery, rearing, production, segregation and breeding or spawning ponds. The area percentage of these ponds in a fish-farming complex can be:
Nursery pond - 3%
Rearing pond - 11%
Production pond - 60%
Segregation pond - 1%
Breeding pond - 25%
Nursery ponds are shallow, while the others are moderately deep. In larger production ponds, water can be maintained at a depth of 2 and 3 metres. A fencing around the fish farm, may be constructed for protection.
Before the culturing of fish, the pond should be conditioned.
A layer of lime (calcium hydroxide) is spread over the bottom, for two weeks. It removes the acidity of the soil, facilitates desirable geochemical cycles and kills unwanted soil organisms.
Water may be let in slowly after two weeks and filled to the desired depth. The quality parameters such as temperature, oxygen content, pH,
turbidity, hardness, alkalinity and plankton growth should be checked for their optimal levels, before stocking the fish.
After 15 days of liming, the fertilization is to be done in order to develop the fish food organisms (phytoplankton and the zooplankton: macro and micro). Manure may be of organic or chemical nature. Organic manure may be urine or sewage rich in nitrogenous matter,cow dung, pig dung, poultry manure and plant manure such as green manure, compost, oil cake etc. If the organic carbon is less, cow dung for the stocking pond is applied at the rate of 2-3 tonnes / ha. Poultry manure at the rate of 5000 kg / ha is known to enhance zooplankton induction. Use of chemical fertilizers should vary according to the concentration of phosphorus and nitrogen in the soil. The standard combination of NPK as 18 : 10 : 4 is generally recommended for freshwater ponds. For a production pond of medium fertile soil; urea at the rate of 200 kg / ha / yr or ammonium sulphate at the rate of 450 kg / ha / yr may be applied in split up dozes, alternating with organic manure.
Feed and water quality are the two major factors governing the productivity of the fish culture pond. Besides, seed quality, stocking and other management measures also determine the extent of fish production.
Water quality involves the regulation of Temperature at 25-33oC, dissolved oxygen, pH (6.5 - 9.0 ), hardness, alkalinity, turbidity and plankton culture etc..
Apart form natural food, most cultured species take artificial feeds. In general artificial feed should contain 30-40% protein, 5-10% fat, 50-60% carbohydrate, less than 5% cellulose, 10% water, vitamins and minerals. Animal and vegetable ingredients can be used in formulating feed pellets. Fishmeal, prawn meal, soybean meal, silkworm pupa, wheat, tapioca, slaughter house wastes, rice bran, aquatic weeds, oilcakes etc are good feed ingredients. Usually Indian farmers give rice bran and oil cakes in powder form to major carps.Carnivorous fishes such as murrels and catfishes may be provided with trash fishes. For adult fish, daily supplementary feeding can be at 2% of its body weight.
Analysing water parameters, replenishment of water, aeration, regular feeding, observation for mortality and disease symptoms should be routine checks in the management of aquaculture ponds. Diseases can be of viral or bacterial origin or may be due to ectoparasites or endoparasites.
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