Water quality decides whether a shrimp crop succeeds. Most problems, from slow growth to disease outbreaks, start with poor pond preparation or water parameters that drift out of range. This guide summarises the basics, drawing on guidance from ICAR-Central Institute of Brackishwater Aquaculture (CIBA).
Pond preparation
- Remove sludge and organic waste from the previous crop, then plough and level the pond bottom.
- Dry the pond: CIBA recommends sun-drying for at least three weeks. Ponds dried for only a few days had more disease problems than those dried for 30 to 45 days.
- Lime the soil based on its pH. The amount depends on the soil and the type of lime used.
Water-quality ranges to watch
- pH: 7.5 to 8.5, with a daily swing of no more than 0.5
- Transparency: 25 to 35 cm on a Secchi disc
- Total ammonia nitrogen: 1 ppm or less
- Nitrite nitrogen: 0.5 ppm or less
- Salinity: avoid daily changes of more than 5 ppt
- Dissolved oxygen: check regularly, especially before dawn
Disinfecting water with chlorine
Farms commonly disinfect reservoir water with calcium hypochlorite before use. CIBA's guidance is about 10 ppm of chlorine: for a 1-hectare reservoir 1 metre deep, roughly 150 to 160 kg of calcium hypochlorite at 65% available chlorine. Work out your own dose from your water's chlorine demand and your product's actual strength, then aerate for at least 48 hours to remove residual chlorine before stocking.
Chlorine is toxic to shrimp, so never stock until the residual has dissipated. Test before stocking.
Liming during the crop
Lime helps stabilise pH and alkalinity during the crop. Agricultural lime (calcium carbonate) and dolomite are gentler; quicklime and hydrated lime act faster and raise pH more sharply, so use them with care and in smaller doses.
Chemicals for shrimp farms
We supply calcium hypochlorite (65–70%), bleaching powder, hydrated lime and aquaculture disinfectants to farms in Andhra Pradesh, Tamil Nadu and Kerala. See also Aquaculture Pond Chemicals.