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	3.2–11.7^c	21.6–31.7	7.35–9.2	0.0–0.2^c	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	3.9–7.7^c	23.3–26.0	6.7–8.6	0.0–1.7^c	12.5–84	0.05–0.34^cc
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	4.4–8.3^c	24.5–30.8	7.2–8.5	0.29–1.6^cc	12.9–113.2^c	0.03–0.33^cc
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	2.3–13.40^c	20.5–28.7	7–8.4	0–1.94^c	0.0–49.2	0–3.06^c
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	0.13–9.1^b	22.7–30.9	6.27^a–7.7	0.12–9.9^cc	17.6–59.2	0.03^b–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	0.13–13.4^b	20.5–31.7	6.27^a–9.2	0–9.9^c	0.0–113.2^c	0.0–3.06^c

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.