- Step 1: Get water into ponds through filter bags made with thick fabric to remove rubbish, larvae, shrimps, crabs, snails, insects, or small fish. Stabilize the ponds in 3-7 days.
- Step 2: Run paddle wheel aerators continuously in 2-3 days to stimulate eggs of shrimp, snails, insects, small fish hatch into larvae.
- Step 3: Kill harmful organisms, sterilize water in settling ponds in the morning (at around 8 A.M.) or the afternoon (16 P.M.) with chlorine with a concentration of 20-30 ppm (20-30kg/1.000m3 of water), or those chemicals allowed to be used in Vietnam (not plant protection products and illegal substances).
Some chemicals that can be used to kill harmful organisms and sterilize water:
- Potassium permanganate (KMnO4): 20-50 kg/ha; spread evenly and leave for at least 24 hours before conducting water coloring.
- BKC (Benzalkonium Chlorinde) 50%: 3-5 ppm (30-50 kg/ha).
- 10% Iodine compounds: 1-3 liters/1.000m3 water.
Note: Use only one of these types of chemicals: or potassium permanganate, or chlorine, or BKC, or iodine. If use chlorine to sanitize the ponds 3-5 days previously, lime should not be used since it raises pH and reduces the ability of chlorine to sanitize.
- Step 4: Use paddle wheel aerators continuously for 10 consecutive days to free chlorine residual. Check the remaining chlorine residual in water with reagents.
- Step 5: Release tilapia into ponds: 50kg unisexual tilapia, size 50g/fish/ 3000m2 of the pond.
- Step 6: Get water from settling pond into farming ponds through filter bags.
Note:
+ For settling pond, maintain farming tilapia continuously throughout the breeding process.
+ Do not get water into farming ponds when: (1) water from cannels has scum, membranes, silt; (2) water in epidemic areas; (3) water that is luminescent at night.
+ Spend special attention to exterminate crustaceans and intermediate hosts (see the techniques above); do not let them get into the pond system
Source: Temporary process for safe brackish-water shrimp farming in areas affected by diseases in Vietnam. According to The Official Dispatch No. 10/TCTS-NTTS. January 6th, 2015. Vietnamese Directorate of Fisheries
Viet Linh 2015. Translated by Sonia Linh V.
