Table 2. The physic-chemical characters of Silurus asotus farm at the monitoring sites from 2018 to 2019
| Variable | 2018 | 2019 |
| Jun. | Jul. | Aug. | Sep. | Oct. | Jan. | Feb. | Mar. | Apr. | May | Jun. | Jul. | Aug. | Sep. | Oct. |
| Water temperature (°C) | 23.8 | 31.7 | 28.9 | 20.8 | 12.4 | 3.4 | 10.7 | 15.8 | 21.0 | 23.0 | 26.1 | 31.3 | 23.7 | 19.9 | 18.1 |
| DO (mg/L) | 8.9 | 3.1 | 7.6 | 7.2 | 9.5 | 12.9 | 13.9 | 12.9 | 13.0 | 10.6 | 7.3 | 5.2 | 4.0 | 5.4 | 7.9 |
| pH | 7.1 | 7.4 | 7.2 | 6.9 | 7.9 | 7.0 | 7.6 | 7.9 | 8.2 | 8.8 | 7.8 | 7.4 | 7.5 | 7.2 | 7.3 |
| NO2-N (mg/L) | 20 | 40 | 20 | 20 | 20 | 0 | 0 | 0 | 0 | 3 | 10 | 80 | 10 | 80 | 40 |
| NO3-N (mg/L) | 20 | 20 | 250 | 250 | 250 | 50 | 25 | 25 | 50 | 10 | 100 | 200 | 200 | 500 | 200 |
| Ammonia (mg/L) | 1 | 2 | 3 | 3 | 2 | 0 | 1 | 1 | 1 | 2.5 | 1 | 2 | 1 | 3 | 2 |
DO, dissolved oxygen.