Fish Husbandry Practices and Water Quality in Central Kenya: Potential Risk Factors for Fish Mortality and Infectious Diseases
Table 2
Mean ± SD values for physicochemical parameters of pond waters in different subcounties of Kirinyaga County.
Subcounties
Physicochemical parameter
Dissolved oxygen (mg/L)
Temperature (°C)
pH
Total ammonia (mg/L)
Nitrate (mg/L)
Nitrite (mg/L)
Kirinyaga Central
Mean ± SD
7.1 ± 2.8
25.9 ± 3.7
7.96 ± 0.7
0.06 ± 0.1
14.4 ± 10.5
0.07 ± 0.05
Range
3.2–11.7c
21.6–31.7
7.35–9.2
0.0–0.2c
0.06–27
0.003–0.15
Kirinyaga West
Mean ± SD
5.8 ± 1.6
24.3 ± 1.1
7.4 ± 0.8
0.35 ± 0.8
43.0–31
0.15 ± 0.13
Range
3.9–7.7c
23.3–26.0
6.7–8.6
0.0–1.7c
12.5–84
0.05–0.34cc
Mwea East
Mean ± SD
6.1 ± 2.0
28.0 ± 3.2
8.07 ± 0.8
0.93 ± 0.9
38.1 ± 50.1
0.12 ± 0.14
Range
4.4–8.3c
24.5–30.8
7.2–8.5
0.29–1.6cc
12.9–113.2c
0.03–0.33cc
Kirinyaga East
Mean ± SD
6.2 ± 2.9
24.2 ± 2.4
7.46 ± 0.5
0.37 ± 0.6
22.4 ± 17.6
0.60 ± 1.08
Range
2.3–13.40c
20.5–28.7
7–8.4
0–1.94c
0.0–49.2
0–3.06c
Mwea West
Mean ± SD
4.4 ± 3.9
26.2 ± 3.2
7.0 ± 0.6
2.98 ± 4.7
37.7 ± 15.4
0.10 ± 0.04
Range
0.13–9.1b
22.7–30.9
6.27a–7.7
0.12–9.9cc
17.6–59.2
0.03b–0.14
County total
Mean ± SD
6.0 ± 2.8
25.3 ± 2.9
7.54 ± 0.7
0.72 ± 1.9
29.4 ± 24.5
0.27 ± 0.7
Range
0.13–13.4b
20.5–31.7
6.27a–9.2
0–9.9c
0.0–113.2c
0.0–3.06c
The optimal ranges of water parameter for fish culture are as follows: dissolved oxygen = 1–5 mg/L; temperature = 20°C–32°C; pH = 6.5–8.5; total ammonia = 0–0.05 mg/L; nitrate = 0–100 mg/L; nitrite = 0.02–0.2 mg/L as described by Bhatnagar and Devi [46]. Note. ccBoth lower and upper values of the reported range exceeded the optimum range. aOnly lower value was below the optimum range. bLower value was below the optimum range and the upper value was above the optimum range. cOnly upper value was above the optimum range. Significantly different () across subcounties.