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3.5.2.1. Water reservoir management and water exchangeIt is recommended to use water for exchange only from a reservoir. Source water is much moreturbid because of drainage from the catchment and the surrounding culture ponds and a reservoir isan essential requirement for management. Water should be left for at least 7 days in reservoir beforepumping to the grow-out ponds. This process helps condition the water and allows suspendedsolids to settle. While pumping the water to grow-out ponds the foot valve of the pump should beplaced at least 30 cm above the pond bottom to avoid any turbidity while pumping. The suction lineshould be placed at the deeper side of the reservoir pond. During water exchange, each time theexchange should not exceed 30% of water in the pond and ideally it should be 10% of the watereach time. This prevents sudden changes in the water quality of shrimp ponds, such as changes inblooms, pH, salinity, and therefore, stress on the shrimp during water exchange is minimized.3.5.2.2. Liming and pH maintenanceDuring the shrimp production cycle, lime should be applied regularly in order to maintain the waterpH. If the water pH falls below 7.5 or fluctuates by more than 0.5 pH units in 24 hours then limeshould be applied. If the pH rises above 8.5, water exchange is needed, followed by application oflime. Lime should be used immediately after every water exchange and after periods of rain. In theinitial stages of culture (when the bloom is not stabilized) dolomite should be applied. After bloomstabilizes (usually after 30-40 days of culture), agricultural lime should be used.3.5.2.3. Fertilization and bloom maintenanceA stable bloom in the pond water is an important factor for health management of shrimp. In earlystages of culture there may be frequent changes in condition of the bloom. This is mainly due tolack of nutrients and carbon dioxide (CO 2). Therefore, nutrients should be supplied in the form offertilizers. Organic fertilizers like cow dung or chicken manure are preferred at early stages ofculture to develop a stable bloom. If only inorganic fertilizers are applied, there will be a suddendevelopment of bloom and subsequent sudden bloom crash. However, a mixture of organic andinorganic fertilizers gives a better bloom at faster rate, which is likely to be maintained for a longerperiod. Fertilizers should always be applied in split dosages for bloom maintenance. During laterstages of culture (after 30 – 40 days of stocking), the pond gets nutrients mainly from waste feedand shrimp excreta and fertilization is not required. However, if there is a sudden changes in bloomdue to changes in climate, such as heavy rain, excessive water exchange and other changes,fertilization may be necessary. If the bloom is very dense, then water exchange should be carriedout.3.5.2.4. AerationAeration should be provided especially in farms (such as those in Nellore district) where the stockingdensity exceeds 6 shrimp m 2 . Aeration is required usually after 30 days of culture and during lateevening to early morning period. Regular aeration is a better practice. In farms with lower stockingdensity (such as those in West Godavari district), low dissolved oxygen is mainly the result oforganic wastes at the pond bottom, especially from un-removed sludge, dead benthic algae andexcessive feeding. In such conditions, aeration should be provided when shrimps start surfacing orthe bottom soil quality is bad and water has more turbidity and dark color.18
Aeration of water using a paddle wheel aeratorIdeal green colored water during grow-out periodClear water with benthic algae at bottomClear water with floating benthic algae3.6. Pond bottom management3.6.1. Risk factorsThe study did not find any direct relationship between the condition of pond sediment and risk ofdisease outbreaks or production. However, in other studies the occurrence of black and toxic bottomsediments has been shown to adversely affect shrimp health and lead to disease outbreak or poorproduction.The study showed there is a relationship between ponds with higher stocking densities and feedingrates, and poor pond bottom conditions. Therefore, as farmers stock with higher density, moreattention must be given to pond bottom management.3.6.2. Management guidelinesThe pond bottom soil should be checked on weekly basis, especially at the feeding area or trench.The occurrence of black soil, benthic algae and bad smell should be recorded. If the soil is blackand smelly, water exchange should be carried out and feed reduced (using a feed tray to monitorrequirements). During water exchange, the feeding area and where black soil occurs should bemidly and carefully agitated to dislodge the soil from the pond bottom. This will facilitate its drainagefrom the pond. Special attention has to be given to management of feed to reduce wastage andavoid deterioration of pond bottoms (see 3.7 - feed management).19
Page 6: ForewordShrimp Aquaculture has prov
Page 10 and 11: AcknowledgementsThe MPEDA and NACA
Page 12 and 13: principles and practices mentioned
Page 14 and 15: Shrimps with loose shell syndromeHi
Page 17 and 18: 3. SHRIMP HEALTH MANAGEMENT GUIDELI
Page 19 and 20: Sludge on pond bottom (indicated by
Page 21 and 22: Table 1. Recommended lime applicati
Page 23 and 24: 3.3.2.2. Fertilization of waterThe
Page 25 and 26: Fast transportation of seed using p
Page 27: The study showed significant relati
Page 31 and 32: Demand feeding using check traysFee
Page 33 and 34: 4. SHRIMP HEALTH MONITORINGShrimps
Page 35 and 36: wwwThe pond water should be treated
Page 37 and 38: 7. FARMER ORGANIZATIONIt is very im
Page 39 and 40: Annex A: Some frequently asked ques
Page 41 and 42: pond, which may help in reducing th
Page 43: Annex B: Crop detail and pond manag
Page 46: Harvest details:Date of harvest:

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