Levels to hold
| Parameter | Level | Basis |
|---|---|---|
| pH | 7–8 at stocking | Ministry of Science and Technology |
| Dissolved oxygen | At least 3 mg/L at stocking | Ministry of Science and Technology |
| Temperature | 28–30 °C at stocking; better rearing at 27–33 °C, optimum 30 °C | Ministry of Science and Technology; Do Thi Thanh Huong et al. 2020 |
| NH3, NO2 | Calculated from pH, temperature and salinity | Toxic gas calculator, select striped catfish |
The pond log on the Tools page marks readings outside the pH, oxygen and temperature levels above.
The higher the pH, the more toxic the ammonia
96-hour LC50 of total ammonia nitrogen (TAN) in 8.1 g fingerlings. These are lethal doses, not safe levels; the lower the number, the more toxic.
- pH 6
- 1,263.2 mg/L
- pH 7
- 257.7 mg/L
- pH 8
- 52 mg/L
The water routine
Disinfect
Run aeration when applying chemicals. Dose by water volume: m³ = area × depth.
Re-seed probiotics
Disinfectants also kill beneficial bacteria. Re-seed after 24–48 hours so they keep breaking down waste.
Minerals and toxic gas
GROWMIN holds alkalinity, YUCCA GRO binds NH3 routinely, YUCCA C when NH3 is high and fish gasp at the surface.
What to measure and when
| When | Task |
|---|---|
| Every morning | Check whether fish crowd at the edge, how they swim, the pond bottom, water colour and feed intake |
| Every day | Check the water so you can act on sudden changes |
| Regularly | Measure pH, NO2 and H2S; intake water must be clean |
| Before stocking | Measure pH, temperature and oxygen; check NH3 and NO2 |
Common situations
Water level
From day 17, raise the water by 15 cm at each treatment. After thinning, exchange water according to actual water quality.
Ponds that are hard to exchange
Fingerling ponds that are hard to exchange or have a lot of bottom organic matter: NIAZYME 1 kg/8,000 m³ for 2–3 days in a row.
First rains
The Ministry of Science and Technology guide advises hydrated lime water (settled) at 20–30 kg/1,000 m², spread over the pond, for the first rains of the season.
Saline water
In a trial on larvae of a Bangladesh stock, mortality rose clearly from 6‰ and all larvae died within 24 hours at 12‰. In salinity-intrusion areas, measure salinity before filling the pond.
Make this schedule for your pond
Enter stocking date, area and depth to get each day's tasks and the kilograms to apply. Open the tools